Osama Bin Laden's son-in-law has pleaded not guilty to plotting against Americans in his role as al-Qaeda's top spokesman.

Sulaiman Abu Ghaith entered the plea through a lawyer to one count of conspiracy to kill Americans after being arrested in Jordan on 28 February.

Abu Ghaith gave an "extensive post-arrest statement" that totalled 22 pages and arrived in the US on 1 March, Assistant US Attorney John P Cronan said.

The prosecutor gave no details on the statement.

Abu Ghaith nodded yes when asked, through an interpreter, if he understood his rights.

He shook his head no when asked whether he had money to hire an attorney.

Bail was not requested, and none was set. The judge said he would set a trial date for 8 April.

Prosecutors said a trial would last about three weeks.

The case marks a legal victory for the Obama administration, which has long sought to charge senior al-Qaeda suspects in US federal courts instead of holding them at the military detention centre at Guantanamo Bay, Cuba.

Charging foreign terror suspects in federal courts was a top pledge by President Barack Obama shortly after he took office in 2009 - aimed, in part, to close Guantanamo Bay.