An alleged militant accused of trying to assassinate Pakistani President Pervez Musharraf has escaped from custody, the authorities say.
A remote bomb exploded just after Musharraf's convoy had passed
Mushtaq Ahmed was being held by air force police in the city of Rawalpindi.
Information Minister Sheikh Rashid Ahmed said he was a key suspect in the failed attempt on the president's life on 14 December 2003.
The president survived two attacks within days of each other, both on the road between Rawalpindi and Islamabad.
He has been a target for Islamic militants since joining the US-led "war on terror" following the attacks of 11 September 2001.
The BBC's Zaffar Abbas in Islamabad says the escape of a man regarded as a prime suspect in the attacks is a huge embarrassment for the authorities.
The authorities accuse Mushtaq Ahmed of belonging to a banned militant group.
Musharraf said al-Qaeda was involved
"This criminal escaped from custody and we hope that we will arrest him. He was a key figure in the 14 December 2003 attack on President Musharraf," Sheikh Rashid Ahmed told the AFP news agency.
He said a huge manhunt was under way.
All airports and other exit points have been put on high alert and Mr Ahmed's photographs have been despatched to border posts to foil any attempt by him to slip out of the country.
Several low-ranking officers of the air force and army were arrested along with Mr Ahmed and a number of other civilians following the attacks.
It is not clear how or when Mushtaq Ahmed escaped and the government gave no details.
Mr Ahmed and the arrested armed forces officials were being tried by a field court marshal when he somehow managed to escape from custody.
Some reports say he has been on the run since November.
President Musharraf survived the 14 December attack, thanks, apparently, to electronic jamming devices which blocked a signal to a remote-controlled bomb.
The blast destroyed a bridge minutes after his motorcade had passed over it. No one was hurt.
Eleven days later two suicide bombers tried to ram explosive-laden vehicles into the president's limousine, killing 17 people.
Last December, one soldier was sentenced to death and another given a 10-year jail sentence for their role in the first of the attacks on the president.
The two men were convicted by a military court in a trial believed to have been held several weeks earlier.