WASHINGTON, US - Senate Minority Leader Mitch McConnell Wednesday defended a Republican measure to prevent bringing five September 11 suspects from their Guantanamo prison to the United States for trial in civilian courts.

'The question is not whether terror suspects should be brought to justice. The question is where and how,' the Republican senator said Wednesday.

'And the answer is perfectly clear: the right forum is military commissions at the secure facility we already have at Guantanamo, not in civilian courts in US communities,' he added.

Last week, the majority Democrats in Congress added language to a Department of Homeland Security appropriations bill that 'prohibits' detainees from being transferred to the United States 'except to be prosecuted.'

The House in June had passed a bill banning the transfer to the United States of any detainee at the US Navy's Guantanamo Bay prison, in Cuba.

The Republican amendment presented Tuesday stipulates that no Justice Department funds can be allotted for 'the prosecution in... (a) court of the United States of an individual suspected of planning, authorizing, organizing, committing, or aiding the attacks on the United States and its citizens that occurred on September 11, 2001.'

McConnell said 'military courts are the proper forum for prosecuting terrorists who violate the laws of war.

'Our past experiences with terror trials in civilian courts have clearly been shown to undermine our national security,' he added.

The senator for Kentucky argued that if convicted and imprisoned in the United States, the Guantanamo detainees would have the right to remain in the country upon their release.

He cited the case of several Chinese Muslims who were cleared of any wrongdoing four years ago, but who are still held at Guantanamo because Washington is unwilling to send them back to China and no country wants to accept them.

The five Guantanamo prisoners suspected of masterminding the September 11, 2001 attacks on the United States are Khalid Sheikh Mohammed, Walid bin Attash, Ali Abd al-Aziz Ali, Mustapha al-Hawsawi and Ramzi Binalshibh.