Turkish authorities have charged 21 people so far

Deputy Prime Minister Abdullatif Sener said that the bombers and those related to them seem to be linked to Osama Bin Laden's network.

More than 60 people died in four suicide attacks which targeted two synagogues, a British bank and the British consulate in Istanbul.

On Sunday, Syria handed over to Turkey 22 people suspected of involvement.

Speaking after a cabinet meeting, Mr Sener said that 21 people had been charged in connection with the bombing so far. Another 16 were still being questioned, in custody.

The government is trying to make excuses for the Turkish Hezbollah. They have to name the name of the terror Deniz Baykal Opposition leader

He did not go into detail on the al-Qaeda connection - the government had previously named it as only "one of the possibilities".

All four suicide bombers in the attacks have now been identified following DNA tests with samples taken from their families.

They were named as Ilyas Kuncak, 47, Mesut Cabuk, 29, Gokhan Elaltuntas, 22, and Feridun Ugurlu.

They were all married, came from the poorer areas of Turkey and at least three of them are reported to have received military training outside Turkey.

Opposition unsatisfied

But the opposition appeared unhappy with the al-Qaeda link.

Prior to the cabinet meeting, the leader of the main opposition party accused the government of not "naming the name of terror".

Republican People's Party leader Deniz Baykal said the Turkish Hezbollah was behind the atrocities, "but the government was trying to make excuses for them".