Officials said an unknown assailant had thrown at least one grenade at Security Secretary Misir Ashirkulov when he was returning home late on Friday in the capital, Bishkek.

Ashirkulov is said to be President Akayev's closest adviser

The attacker escaped and the motive behind the assault remains unclear.

There has been a wave of civil unrest in Kyrgyzstan since March, when five people were killed in clashes with police during a protest rally.

A special commission's report blaming officials for the deaths led to the resignation of the cabinet in May.

But critics have blamed President Akayev for the killings and called for his resignation.

'Presidential successor'

Mr Ashirkulov, who is Security Council secretary and head of the presidential administration, is said to be one of the most influential officials in Kyrgyzstan.

Some reports say the president is preparing Mr Ashirkulov to be his successor.

Mr Ashirkulov is being treated in hospital for severe injuries.

A spokesman for the Interior Ministry said he was in satisfactory condition after undergoing an operation.