Global intelligence and police agencies are on a worldwide hunt for terrorists with ties to places as disparate as Boston, Islamabad, and Panama City, part of a U.S. scramble to head off what officials fear could be a massive attack this summer.

The U.S. Justice Department (search) released a list of seven people wanted for questioning Wednesday after authorities received a stream of credible intelligence reports pointing to a terror attack of Sept. 11 proportions in the United States this summer. U.S. Attorney General John Ashcroft (search) asked American citizens to give any information they can, and foreign governments have been recruited.

Those on the list include a man who grew up on a goat ranch in California before converting to Islam; a Tunisian who obtained Canadian citizenship; a Tanzanian who goes by the names "Foopie," "Fupi" and "Ahmed the Tanzanian;" a Pakistani woman who received a biology degree in Boston; and a native of the Comoros Republic in the Indian Ocean who is believed to be Al Qaeda point-man in eastern Africa.

Even Panama, a country known more for its canal than terrorism, has been included in the search. Officials said Wednesday they are trying to track down a man identified as Adnan Gulshair El Shukrijumah, of Saudi Arabia.

Panamanian Security Council Chief Ramiro Jarvis said El Shukrijumah arrived in Panama legally from the United States in April 2001 — five months before the Sept. 11 terror attacks — and stayed in Panama for 10 days. He also visited Trinidad and Tobago for six days the next month.

"We don't know exactly what he did during his stay and it is important to find out," Jarvis said.

Migration records show El Shukrijumah returned to the United States, Interior Department spokesman David Salayandia said. The last place he was seen, however, was in Panama.

The revelation was one of the few indicators that have tied Latin America to the global terrorism threat. Officials have long worried that terrorists would use the region to attack the United States, but so far there has been little evidence to support that fear.

Two of the suspects were also from Canada, according to Canadian Deputy Prime Minister Anne McLellan. She said there was no evidence they are currently in the country, but she urged Canadians to report suspicious activity.

"We know that we are not immune to terrorism, and that we must be vigilant," she said.

One of the men, Abderraouf Jdey, a Tunisian who obtained Canadian citizenship in 1995, was among five people who left suicide messages on videotapes recovered in Afghanistan at the home of Mohammed Atef. Atef, reportedly Usama bin Laden's military chief, was killed in a U.S. airstrike in 2001.

Pakistani security officials are also looking for information on Aafia Siddiqui, 32, a Pakistani woman who received a biology degree from the Massachusetts Institute of Technology and wrote a doctoral thesis on neurological sciences at Brandeis University, outside Boston, in 2001.

Authorities say she returned to Pakistan shortly after the Sept. 11 attacks with her husband and three children. Her whereabouts have been a mystery since March 2003, when the FBI issued a global alert for her arrest for possible links to Al Qaeda (search). The FBI also wants to talk to her husband.

U.S. authorities have not alleged that Siddiqui is a full-fledged member of Al Qaeda, but believe she could be a "fixer" — someone with knowledge of the United States who can support and help get things done for other operatives.

A senior Pakistani security official told The Associated Press on Wednesday that the United States had made no new request for Pakistan to find Siddiqui but that one issued last year was still in effect despite turning up nothing at the time. The official said she had gone underground, and it wasn't even known if she was still in Pakistan.

Another suspect is Ahmed Khalfan Ghailani, under indictment in the United States for the 1998 Al Qaeda bombings of U.S. embassies in Kenya and Tanzania. The Tanzanian also goes by the names "Foopie," "Fupi" and "Ahmed the Tanzanian." He is under

A 25-year-old U.S. citizen, Adam Yahiye Gadahn, is also a suspect. He goes by the names Adam Pearlman and Abu Suhayb Al-Amriki. FBI Director Robert Mueller says he attended Al Qaeda training camps and has served as an Al Qaeda translator.

Gadahn says on an Islamic Internet site that he grew up on a goat ranch in Riverside County, Calif., and converted to Islam in his later teenage years after moving to Garden Grove, Calif.

Although El Shukrijumah appears to have left Panama, the tiny country is still looking for evidence he might have returned.

"His whereabouts are unknown, but we are on alert," Jarvis said, adding that authorities were tightening security at airports and along the country's borders.

Believed to be 29 years old, El Shukrijumah was once a legal U.S. resident of the United States and his father lives in Florida.

In March 2003, the FBI said it wanted to question El Shukrijumah on suspicion of involvement in plotting Al Qaeda attacks on the United States, but that he faced no formal charges.

The attention last year led to the firing of El Shukrijumah's father, Gulshair Muhammad El Shukrijumah, from a leadership position at a U.S. mosque in Miramar, Florida. His father said then that when he last talked to his son, in 2002, he was teaching English in Morocco.

U.S. authorities have said they are working to establish links between El Shukrijumah and other terror suspects, including Jose Padilla, an American arrested in 2002 for allegedly plotting to detonate a radioactive bomb. The two apparently both lived in south Florida in the 1990s.

U.S. authorities have said El Shukrijumah has many aliases and may be carrying passports from Saudi Arabia, Trinidad and Canada. Police in Guyana have said he also holds a valid passport from that South American country, where his father was born.

"It's incredible how these people move from place to place," said Panamanian housewife Irma Rivas, 37, after she heard the news. "Now it's not safe anywhere."