At least 15 people, including a judge, were killed and 24 injured when a suicide bomber blew himself up in a courtroom in Quetta in Pakistan.

Quetta, the capital of the troubled Balochistan region, is reeling under a spate of attacks.

Soon after the bomb attack in the high security area, security officials in Sukkar in Punjab province detained three persons who were allegedly in touch with the bomber, Geo TV reported.

The bomber allegedly entered the courtroom and blew himself up. Senior judge Abdul Wahid Durani, several lawyers and the bomber were killed in the suicide attack, Balochistan police chief Tariq Khosa said.

The police also recovered the head of the suicide bomber who was described as bearded with Afghani features.

Police suspect him to be an Afghan refugee or from the tribal Waziristan agency where al Qaeda and Pakistan Taliban are well entrenched.

Pakistan is reeling under a spate of suicide bombings since January, but this is the first such attack in restive Balochistan where US and Afghanistan alleged that Taliban leaders had their bases.

The attack comes a day after the arrest of three suicide bombers in Karachi from whom jackets used in bombings besides explosives, ammunition and an Ak-47 rifle were seized.

The three, belonging to a banned pro-Taliban outfit, were remanded to police custody by local court after police said they needed them for interrogation to find the whereabouts of seven other suicide bombers.

A red alert had already been sounded in capital Islamabad with intelligence reports stating that several suicide bombers had sneaked into the city to target some high profile leaders.

On January 26, a bomber blew up at the emergency exit of Marriot hotel hours before the Indian Republic Day reception was held. Subsequently a suicide bomber struck in Peshawar killing the local police chief. Similar attacks were carried out on army convoys and Islamabad airport. Police have determined the identity of the airport suicide bomber and were probing his links with different militant groups.

President Pervez Musharraf and Prime Minister Shaukat Aziz have strongly condemned the Quetta blast and expressed the government's firm resolve to strictly deal with the terrorists.

In a message, Musharraf expressed grief over the loss of innocent lives and directed the provincial administration to provide all possible medical assistance to the injured.

Balochistan has witnessed widespread violence following military operation against Baloch nationalists who have attacked government and military installations to press their demand for autonomy and an increased share of mineral resources from the gas and oil rich province.