Washington  - US authorities announced arrests in two cases where undercover agents supplied bogus bombs to would-be terrorists who attempted to set off the devices against targets in Illinois and Texas.

In Springfield, Illinois, Michael Finton, 29, a convicted felon who converted to Islam in prison, was charged Thursday with attempting to bomb the federal courthouse, a few blocks from the Illinois State Capitol.

He had been under federal surveillance for two years until his arrest on Wednesday, moments after he planted and tried to detonate a dummy car bomb that was supplied by an undercover agent with the Federal Bureau of Investigation posing as an operative from the terrorist network al-Qaeda.

Thursday's hearing took place in the same federal building where prosecutors alleged that he had parked the supposedly bomb-laden vehicle on Wednesday.

In Dallas, Hosam Maher Husein Smadi, a 19-year-old Jordanian, was arrested Thursday after allegedly parking a purported car bomb at Fountain Place, a 60-story building in the Texas metropolis. He faces a charge of attempting to use a weapon of mass destruction.

Smadi, who was in the United States illegally, had come to the attention of federal agents for his militance in internet chat groups.

Federal prosecutor James Jacks said Smadi was working alone. The inactive car bomb he allegedly planted was supplied by undercover agents.

The Illinois and Texas cases followed Thursday's indictment of Najibullah Zazi, 24, a legal permanent US resident of Afghan origin who was arrested Saturday. The shuttle driver in Denver, Colorado, faces charges of conspiring to use weapons of mass destruction in the United States, the Justice Department said.

Zazi's arrest took place after federal agents conducted raids in Colorado and New York over a possible plot to detonate bombs on public transportation targets.

According to officials, Zazi admitted to attending an al-Qaeda facility in the tribal areas of Pakistan last year, where he received training in the use of weapons and explosives.

Court documents said he drove to New York last week with a computer that contained instructions on bomb assembly.

All three suspects could face life in prison if convicted. (dpa)