The first Guantanamo Bay detainee to be brought to the United States for trial has pleaded not guilty to involvement in the deadly 1998 bombings of two U.S. embassies in Africa.

Ahmed Ghailani entered the plea Tuesday afternoon in federal court in lower Manhattan. He was brought to the United States under heavy guard earlier in the day.

"With his appearance in federal court today, Ahmed Ghailani is being held accountable for his alleged role in the bombing of U.S. embassies in Tanzania and Kenya and the murder of 224 people," Attorney General Eric Holder said in a press release.

"The Justice Department has a long history of securely detaining and successfully prosecuting terror suspects through the criminal justice system, and we will bring that experience to bear in seeking justice in this case."

Ghailani's trial will be an important test case for the Obama administration's plan to close the detention centre at Guantanamo in seven months and bring some of the suspects to trial.

Ghailani was indicted in 1998 for the al-Qaeda bombings of U.S. embassies in Kenya and Tanzania, attacks that killed more than 224 people, including 12 Americans.

Four other men have been tried and convicted in the New York courthouse for their roles in the embassy attacks. All were sentenced to life in prison.

Rose through the ranks

U.S. officials charge Ghailani began his terrorist career delivering bomb parts on a bicycle, and rose through the al-Qaeda ranks to become a bodyguard to Osama bin Laden.

Ghailani, a Tanzanian, was in his 20s when prosecutors say he helped terrorists build one of the bombs that destroyed U.S. embassies in East Africa in 1998.

He left Africa just before the bombings, according to investigators.

The Obama administration is trying to put him into the U.S. criminal justice system, despite claims by Republican critics that doing so would endanger American lives. Some legislators have opposed bringing any Guantanamo detainees to the U.S. for trial, even in heavily guarded settings.

Last month, President Barack Obama said that preventing Ghailani from coming to U.S. soil "would prevent his trial and conviction. And after over a decade, it is time to finally see that justice is served, and that is what we intend to do."

But Obama faces pressure from across the political spectrum on his plan to close the detention centre. Democrats have said they want to see the president's plan for closing the base before approving money to finance it, and Republicans are fighting to keep Guantanamo open.

Canadian Omar Khadr has been held at the prison since 2002 and is accused of killing a U.S. soldier during a fight in Afghanistan. On July 13, a U.S. army judge is expected to rule on a request from Obama for a 120-day suspension in his case.

The president has asked for suspensions in all pending Guantanamo cases, to keep them on hold until September.

That would give Obama time to introduce changes to the tribunal system designed to give stronger legal protections to the detainees. So far, nine of the 11 active cases at Guantanamo have been granted suspensions.