Updated

As hundreds of Al Qaeda militants in Yemen are said to be planning terror attacks against the West, a U.S. lawmaker has called on the Obama administration to halt immediately the release of Guantanamo detainees to the Middle Eastern country.

Rep. Frank Wolf, R-Va., wrote to President Obama Tuesday requesting that the administration not send any more Guantanamo detainees back to Yemen or any other unstable country. Wolf, who has penned four similar letters since Oct. 1, said he also would ask that threat assessments be made public for each detainee who is cleared for release.

"I'm troubled by every [detainee] that I've read about," Wolf told FoxNews.com. "I personally would have sent none of them back to Yemen. These guys are some of the most dangerous; they've been involved in activities with direct threats to the United States....

"Don't send them back to Yemen, particularly based on what happened on Christmas," he said. "It's dangerous to the country."

Republican Sens. Lindsey Graham of South Carolina and John McCain of Arizona and Sen. Joe Lieberman, I-Conn also wrote to Obama on Tuesday making the same case.

"Given the security situation in Yemen and the failure of the Yemeni government to secure high-value prisoners in the past, we believe that any such transfers would be highly unwise and ill-considered," the senators said.

Abu Bakr al-Qirbi, Yemen's Foreign Minister, told the Times of London on Tuesday that Yemeni authorities are aware of Al Qaeda operatives in the country, including some leaders.

"They may actually plan attacks like the one we have just had in Detroit," he told the paper. "There are maybe hundreds of them -- 200, 300."

Al-Qirbi's comments came one day after Yemen-based Al Qaeda in the Arabian Peninsula claimed responsibility for the failed attempt to blow up a Detroit-bound plane on Christmas Day.

Umar Farouk Abdulmutallab, the suspect in the bombing attempt, spent time in Yemen with Al Qaeda and was in the country only days before the attempted attack.

Just five days earlier, the U.S. Department of Justice announced the transfer of 12 Guantanamo detainees to Afghanistan, Yemen and the Somaliland region. The six detainees released to Yemen were identified as: Jamal Muhammad Alawi Mari, Farouq Ali Ahmed, Ayman Saeed Abdullah Batarfi, Muhammaed Yasir Ahmed Taher, Fayad Yahya Ahmed al Rami, and Riyad Atiq Ali Abdu al Haf.

Dean Boyd, a spokesman for the Department of Justice, said 14 Guantanamo Bay detainees were transferred to Yemen during the Bush administration and seven others had been released to the country since Obama took office.

"The U.S. Government would not have proceeded with these transfers if there were security-related concerns that were not adequately addressed," Boyd wrote in an e-mail to FoxNews.com regarding the most recent detainees to be transferred. "The transfers were carried out under individual arrangements between the United States and the Government of Yemen to ensure the transfers took place under appropriate security measures."

Meanwhile, a Yemeni Al Qaeda faction -- whose masterminds were released from Guantanamo Bay -- claimed responsibility for orchestrating the Christmas Day terror attempt.

Said Ali al Shihri and Muhammad al Awfi were captured in Afghanistan in late 2001, ABC News reported, and were  freed from Guantanamo in November 2007. They promptly began conspiring against the United States after completing an "art-rehabilitation" therapy in Saudi Arabia as a condition of their release.

"The so-called rehabilitation programs are a joke," a U.S. diplomat told ABC.

Al Shihri and Al Awfi reportedly belong to the group Al Qaeda in the Arabian Peninsula, which is led by Usama bin Laden's former personal secretary. The group, known as AQAP, posted a statement on its Voice of Jihad Web site boasting it had overcome the sophisticated U.S. security and intelligence.

Al Awfi reportedly turned himself into Yemeni authorities in February, and al Shihri may have been killed in one of two recent attacks on Al Qaeda strongholds.

Kirk Lippold, former USS Cole commander and senior military fellow at Military Families United (MFU), said reports that the former detainees worked with Abdulmatallab is the "clearest indication" yet that continual release of Guantanamo Bay detainees is an unacceptable risk to Americans.

"As a nation, we cannot rely on so-called 'reform camps' in places like Saudi Arabia to prevent terrorists from striking again," Lippold said in a statement. "The President promised the victims of terrorism and the American people a clear strategy for how he intended to fight terrorism and deal with detainees in [Guantanamo]. Almost a year into his term, neither objective is close to being achieved."

Lippold called on administration officials not to release any additional detainees from Guantanamo.

"The President’s strategy of increasing risk to American lives as part of some indescribable national security strategy to defeat Al Qaeda must be refocused," the statement continued. "The Administration’s position on [Guantanamo Bay] is the centerpiece of this perilous strategy."

Here's a closer look at the six detainees recently released to Yemen:

Jamal Muhammad Alawi Mari

Apprehended during a raid of his home in Karachi, Pakistan, on Sept. 23, 2001, Mari admitted he was a director of the Baku, the Azerbaijan branch of the Al Haramayn, a non-governmental organization with known Al Qaeda connections. According to Department of Defense documents, Mari admitted traveling to Afghanistan in May 2001 to work as a director for Al Wafa, also a non-governmental organization with known ties to Al Qaeda. He was transferred to his native Yemen on Dec. 19.

Farouq Ali Ahmed

Ahmed, 26, was captured by Pakistani forces as part of an organized group of 30 Mujahideen after the fall of Tora Bora near the Pakistan-Afghanistan border in December 2001. Ahmed traveled from Yemen to Afghanistan in March 2001 and was observed carrying an AK-47 while wearing fatigues near Usama bin Laden's private airport in Kandahar, Afghanistan, according to Department of Defense documents.

Dr. Ayman Saeed Abdullah Batarfi

Captured in Afghanistan in January 2002, Batarfi, 39, had been detained for seven years prior to his release this month. Batarfi, who once practiced medicine in Afghanistan, had previously been accused by the Bush administration of taking part in Al Qaeda's anthrax program. U.S. officials later backed off that accusation but continued to allege in Combatant Status Review Tribunal documents that Batarfi had once worked for a charity that had terrorist ties and that he personally met with Usama bin Laden in Tora Bora in November 2001.

Muhammaed Yasir Ahmed Taher

Taher, 29, was captured in Pakistan in March 2002. According to court documents, he stated that he was a terrorist and traveled to Yemen from Pakistan in September 2001 in association with the Jama'at al-Tablighi, a Pakistan-based Islamic missionary organization used as cover to mask travel and terrorism activities of Al Qaeda members. A senior Al Qaeda lieutenant once recognized Taher in a photograph, court documents say. He is the younger brother of Salah al Salami, a Guantanamo Bay detainee found dead in his cell in June 2006.

Fayad Yahya Ahmed al Rami

Al Rami -- believed to be in his early 30s -- was captured in Pakistan in March 2002. According to court documents, Rami was recruited by a member of Jama'at al-Tabligh and had traveled to Pakistan from Yemen prior to Sept. 11, 2001.

Riyad Atiq Ali Abdu al Haf

Al Haf -- also listed in court documents as Riyad Atiq Abdu al Haj -- was captured near the Pakistan-Afghanistan border in late 2001. He was previously determined to be a Taliban supporter -- possibly a courier or recruiter -- and admitted that he agreed to serve the Taliban, according to Department of Defense documents. After voluntarily traveling to Afghanistan from Yemen, al Haf was apprehended in a car by a group of Taliban associates and driven to Kandahar, Afghanistan, where he stayed in a Taliban guest house for up to 3 weeks. Al Haf was also believed to have participated in military operations against coalition forces.