A blast on Thursday rocked a military building in northwestern Pakistani town of Tarbela, close to the capital Islamabad, killing at least 15 army men, officials said.

The explosion took place in a dining area of the military commandos "Special Services Group" in Tarbela, reportedly scores of kilometers south of Islamabad, killing 15 army men and injuring several others, the military spokesman Major General Waheed Arshad said.

However, the private DAWN NEWS TV channel quoted a tehsil nazimas saying that some 20 people were killed and 44 others injured.

Details of the blast are still not available and there has been no immediate responsibility claim.

Arshad earlier said an investigation will be conducted to determine the cause of the blast.

Private Geo TV channel reported that the incident was believed to be a suicide attack.

The area was cordoned off after the blast and the injured have been rushed to local hospital. High-security alert has been put in nearby military areas.

The incident came a day before the beginning of Muslim fasting month Ramazan on September 14, as security arrangements in major cities including Islamabad and garrison city Rawalpindi have been intensified.

Pakistan has seen a sharp increase of bomb attacks, mostly targeting security personnel, since July when a government operation stormed Islamabad-based hard-line Red Mosque. Over 300 people, mostly security personnel, were killed in various bomb attacks over the two months.

Pakistan joined Washington-led war on terror following September 11, 2001 attack on the US, and has since sent around 90,000 troops to its northwestern border areas to hunt al-Qaida and Taliban remnants who sneaked into Pakistani soil for shelter after the Afghan Taliban regime fell.

Pakistani President Pervez Musharraf on Thursday reaffirmed Pakistan's firm resolve to fight extremism and terrorism, saying it was in the county's national interest, while talking to visiting US Deputy Secretary of State John D. Negroponte, according to an official statement issued earlier.

(Xinhua News Agency September 14, 2007)