DEARBORN— A judge has ordered monitoring of computer and Internet use of a U.S. Islamic preacher regarded by some federal officials and a group that studies radicals as an inspirational figure for foreign fighters in Syria.

The close supervision of Ahmad Musa 

Jebril.

, 43, was ordered  after a court hearing last Thursday. At the hearing he was deemed to have violated conditions of his early release from a lengthy prison sentence imposed for fraud and jury tampering.

In a written order he issued after the hearing in Detroit, Federal Judge Gerald Rosen did not link his decision to Jebril’s online preaching.

But federal officials familiar with the case told Reuters the judge’s order would allow probation authorities to monitor Jebril’s activities to make sure he is not trying to instigate Americans to travel to Syria to join other foreign fighters. The officials spoke on condition of anonymity because they were discussing sensitive information.

Other officials said U.S. authorities were stepping up efforts to track and investigate Americans who go to Syria to join rebels trying to oust President Bashar al-Assad, and estimated that several dozen Americans had done so.

Security authorities in some European countries, including Britain, Belgium, the Netherlands and Germany, say hundreds of their citizens have done likewise.

The Justice Department, the Federal Bureau of Investigation and U.S. spy agencies have recently assigned coordinators or special teams to monitor such travel, fearing that radicalized Americans may return and stage attacks at home.

This month, U.S. authorities said that a Florida man, Moner Mohammad Abu-salha, had become the first known American suicide bomber in Syria. Social media postings from purported militants indicated he carried out a suicide bombing in Idlib province on May 25 by Jabhat al-Nusra, an al Qaeda-affiliated group.

Federal probation authorities had said Jebril violated the terms of his early release by not informing them fully about a trip he made to North Carolina, when he failed to disclose that he was going to make speeches on Islamic topics.

Judge Rosen ordered Jebril not to travel outside eastern Michigan and to wear an electronic tracking device. He said Jebril must provide his probation officer with information about his computer systems and Internet services providers, as well as his passwords for such systems.

In April, a London think tank that specializes in studying radicals and violence described Jebril as one of two English-speaking “spiritual authorities” who were inspirational figures for foreigners fighting in Syria.