A U.S. congressman is the latest to call for a Justice Department investigation into whether a pro-Palestinian group has been raising money on college campuses for Hamas.

In a letter to U.S. Attorney General Eric Holder, Rep. Brad Sherman (D-Calif.) urged a probe into Viva Palestina USA, a humanitarian aid convoy led by British lawmaker George Galloway that brought medical supplies to Gaza last July.

Both the Zionist Organization of America and Anti-Defamation League in recent months have urged Holder to investigate reports about the convoy's links to Hamas.

The groups made their requests after Galloway and other Viva Palestina USA members appeared and reportedly raised funds at some college campuses in the spring and summer.

"Clearly, people and organizations in the United States cannot be allowed to solicit funds for foreign terrorist organizations," Sherman wrote in his letter to Holder. "That such solicitation is occurring during the middle of the day at a public university is truly frightening," he said, referring to the University of California, Irvine.

Sherman wrote similar letters expressing concern about the reports on Viva Palestina USA to Secretary of State Hillary Clinton, University of California, Irvine chancellor Michael Drake and Internal Revenue Service commissioner Douglas Shulman.

Viva Palestina USA was launched after the Viva Palestina group that Galloway set up in Britain sent a convoy to Gaza in March. It did not respond to request for comment.

At a meeting in Gaza with Hamas officials during the March trip, according to a report from terrorism expert Steve Emerson, Galloway held up a bag of cash and said “This is not charity. This is politics” and “We are giving this money now to the government of Palestine. And, if I could, I would give them 10 times, 100 times more."

When the Viva Palestina USA convoy arrived in Gaza months later, there was no similar public event with Hamas, although the group reportedly did meet with Hamas leader Ismail Haniyeh.

Giving humanitarian aid to Gaza is legal under U.S. law, but providing it to Hamas officials or the Hamas government in Gaza would likely be considered illegal because Hamas is on the list of foreign terrorist organizations.

The most controversial appearance by Viva Palestina USA and Galloway in the United States came May 21 at the University of California, Irvine, a campus that has experienced tensions between Jewish and Muslim students and where a civil rights complaint was filed earlier this decade claiming a hostile environment for Jewish students. (A federal investigation found that the university acted appropriately.)

UC-Irvine has referred information about the event, which was sponsored by the Muslim Student Union, to the Federal Bureau of Investigation. ZOA leaders said they had obtained a video of the event and, at the bureau’s request, passed it on to law enforcement officials.

The university also says it is investigating whether the Muslim Student Union had violated university policy by raising money without the university's authorization.

In a letter to the university's campus counsel, the Muslim Student Union acknowledged that it may have "unknowingly breached university policy (as undoubtedly have every student organization on campus as well as university administrators)." But the student group rejected ZOA's accusations that it may have raised money for Hamas as "nothing short of libel."

"ZOA seeks to smear MSU's reputation by maliciously accusing MSU of breaking U.S. laws without providing any real evidentiary backing," the group said in its letter.

The ZOA praised the university's decision to forward information on the Viva Palestina fund raising.

“They've done the right thing,” said Susan Tuchman, director of the ZOA's Center for Law and Justice. “All groups should be held accountable.”

University spokeswoman Cathy Lawhon said the campus police forwarded information on the Viva Palestina fund raising to the FBI because it felt “they were the best agency to handle it.” She said outside counsel is examining whether the Muslim Student Union violated campus procedures.