An associate of Abu Musab al-Zarqawi (search) has been captured in the Baghdad area, a defense official confirmed to Fox News on Tuesday.

The name of the associate was not released but he was described as a midlevel terrorist operative.

Zarqawi, who is still at large, and his group have been linked to Al Qaeda (search) by the United States -- Zarqawi himself a senior associate of Usama bin Laden.

Zarqawi is believed to have traveled through Iran to Iraq in May and June of 2002 for medical treatment following the collapse of Al Qaeda operations in Afghanistan.

Administration sources, speaking on condition of anonymity, said he had his leg amputated.

The capture of Zarqawi's associate occurred this week, a counterterrorism official said. Zarqawi is among the administration's most-wanted Al Qaeda figures.

Zarqawi ran a training camp in Afghanistan for poisons, and has been linked to efforts in northern Iraq and Europe to produce and employ the biotoxin ricin.

The United States has accused Zarqawi, a Jordanian, of having been the mastermind behind the assassination of American diplomat Lawrence Foley (search) in Amman last October.

Before the military action in Iraq began, Secretary of State Colin Powell suggested that Zarqawi's activities were evidence of ties between Al Qaeda and Iraq. Powell also said that Zarqawi's Al Qaeda-linked group was operating inside Baghdad.

In February, Powell testified before the U.N. Security Council that as Baghdad harbored Zarqawi, several of his underlings set up operations in the Iraqi capital to help shift money, supplies and personnel around the country.

Iraq's ambassador to the United Nations before the fall of Saddam's regime, Mohamed Al-Douri (search), denied all of Powell's accusations.

Powell charged that after Al Qaeda and Taliban (search) forces were defeated by U.S. troops in Afghanistan, Zarqawi founded the camp in northern Iraq to train terrorists in the use of poisons and explosives.

Powell also said in his testimony before the United Nations that Washington, through an intermediary, supplied Baghdad with enough information to shut Zarqawi's operation down multiple times -- but "Zarqawi still remains at large to come and go."

During Zarqawi's stay in Baghdad, several of his associates, affiliated with Egyptian Islamic Jihad, joined him in the city. The Egyptian Islamic Jihad is considered merged with Al Qaeda.

It is unclear if the captured operative was one of those associates.

Zarqawi left Baghdad, but those associates remained, officials have said. His current whereabouts are unknown.

Both Zarqawi and the captured man are also suspected of links to Ansar al-Islam, an Islamic extremist group in northern Iraq composed of ethnic Kurds. The group's camps were bombed heavily by U.S. forces during the war.

Officials suspect Zarqawi is linked to a plan to use poison against European targets late last year. They also say he took part in a foiled plot to bomb a tourist hotel in Amman, Jordan, during millennium celebrations.

The Associated Press contributed to this report.