US officials had said at the time the grenade failed to explode only because of a malfunction and landed within 30m of Bush as he spoke to tens of thousands of people in Tbilisi's Freedom Square.

The Georgian Interior Ministry released a tape made on Thursday showing the suspect, identified only as Arutunyan, confessing.

Asked by an official whether he threw the grenade, Arutunyan, who looked calm, replied: "Yes."

Valid confession?

Deputy Health Minister Irakly Giorgobiani said: "Doctors, who talked to (him) yesterday, said that he had confessed that he had thrown a grenade. But they also said that he may not have been in control of himself at the time."

One man was killed in an operation
to arrest the suspect

Georgian police detained the man on Wednesday after a special operation in which an anti-terrorism officer was killed and the suspect wounded.

Giorgobiani told Rustavi-2 TV the suspect's condition was now normal and there was no threat to his life.

Interior Minister Vano Merabishvili told a briefing the investigation was continuing and that a reward of about $83,000 would be split among several people who helped the investigation.

Joint operation

The security scare marred Bush's trip to Georgia, intended to show US support for the West-leaning government that came to power after a democratic revolution 20 months ago.

Officials said the grenade could have caused major injuries in the close-packed crowd, the largest gathering of people on the square since the "Rose Revolution" led by now-President Mikhail Saakashvili.

The US Embassy in Georgia said in a statement on Thursday
that co-operation on the case was "a model" for joint work by
law-enforcement agencies of the two countries.