Sami Amin al-Arian was led in handcuffs to the FBI headquarters in Tampa, Florida, yesterday, accused of being the American leader of the Palestinian-based Islamic Jihad and the secretary of its worldwide council.

The indictment charges Mr al-Arian and seven others with operating a criminal racketeering enterprise since 1984 that supported Islamic Jihad - which is held responsible for the deaths of more than 100 people in and around Israel, including two American citizens.

It also accuses them of engaging in conspiracy to kill and maim people abroad, conspiracy to provide material support to the group, extortion, perjury, and other charges.

"It's all about politics," said Mr al-Arian as FBI agents led him away.

Two others were arrested in Tampa, and one in Chicago. Another four live abroad. It was not immediately clear whether they had been taken into custody last night or not.

In announcing the indictment, the attorney general, John Ashcroft, said the eight men supported numerous violent terrorist activities.

"Our message to them and to others like them is clear: We make no distinction between those who carry out terrorist attacks and those who knowingly finance, manage or supervise terrorist organisations," he said.

Each defendant faces life in prison if convicted.

Mr al-Arian has lived in America for 28 years and has never been convicted of a crime, but has been under federal investigation because of his pro-Palestinian activism for several years. He ran an Islamic charity and a thinktank in Tampa in the early 90s.

He initially came under scrutiny after news reports revealed that the charity had sponsored conferences at which he and other speakers shouted "Death to Israel," "Damn America," and called for donations to support continued attacks in Israel. The authorities said some of the speakers were leaders of the Palestinian Islamic Jihad.

Mr al-Arian's brother-in-law, Mazen al-Najjar, who ran the thinktank, and who had also taught at the university, spent more than three and a half years in jail on secret evidence linking him to terrorists. He was released in 2000 but arrested again in November 2001 and deported last August.

The University of South Florida, where Mr al-Arian had taught computer engineering for more than 10 years, banned him from the campus shortly after September 11 and then suspended him from his tenured post and started the process of trying to fire him. After a flood of emails and phone calls protesting against his presence there after September 11 they claimed his activities both endangered the safety of students and impeded their ability to raise money.

Their decision sparked outrage from the Muslim and academic communities as well as civil liberties organisations who regarded the move to sack him as an infringement of freedom of speech prompted by nationalist hysteria.

Mike Pheneger of the American Civil Liberties Union, the country's largest civil rights advocacy group, said: "[They have] allowed the calls of anonymous people and their anonymous threats left on answering machines to dictate a policy that says speech is only free if it's not controversial."

Last February, the New York Times ran an editorial saying: "The First Amendment protects not only those whose ideas Americans like but, more important, those whose ideas they abhor. Free speech and academic freedom must be blind to politics. Firing a professor because his views are causing others to criticise or threaten the university is a betrayal of the academic code. No campus should be run that way."

The American Muslim Alliance, a coalition of Muslim-American groups, said the university's stance showed "bigotry and prejudice against the entire Muslim community."

In June, the Washington-based American Association of University Professors strongly criticised the university. William Van Alstyne, a professor at Duke University School of Law, who heads a committee investigating the issue, said that even if the government did accuse Mr al-Arian of a crime, an indictment, "though a serious matter, would not establish wrongdoing."

"It would be wrong to terminate him from a public institution just on the basis of that," said Mr Alstyne.

Last month, the university's union filed a grievance on Mr al-Arian's behalf, saying that banning him from campus violated the union's contract, his right to academic freedom and its own policy of non-discrimination on the basis of ethnicity and religious affiliation.