Islamabad - Pakistani President Asif Ali Zardari on Sunday left Islamabad to attend the 63rd UN General Assembly session, a day after the country's worst terrorist attack took place in the city, killing at least 50 people and wounding more than 250 more.

Zardari is also expected to meet US President George W Bush in New York on Tuesday to discuss the war strategy and US incursions in inside Pakistan to hunt down al-Qaeda and Taliban militants.

Pakistani Foreign Minister Shah Mahmood Qureshi and Information Minister Sherry Rehman are part of the entourage accompanying the president in the five-day visit, officially starting from Monday.

Zardari on Saturday addressed a joint session of the country's bicameral parliament and vowed to "root out terrorism and extremism wherever and whenever they may rear their ugly heads."

He said Pakistan would not tolerate intrusion "by any power in the name of combating terrorism," in a direct reference to increasing airstrikes by US forces operating in Afghanistan, who also carried out their first ground attack on September 3.

Hours after Zardari declared his resolve to quell militancy in Pakistan, a truck suicide bomber attacked the Marriott luxury hotel located just over a kilometre from the presidential and prime ministerial palaces, where Pakistan's top civilian and military leaders were attending a dinner party.

Analysts see the surge in countrywide bombings as a reprisal from militants in Pakistan's north-western regions, where government forces are using ground and air power to strike rebel positions.

The tribal areas near the Afghan border are considered a hotbed of al-Qaeda and Taliban militants who launch cross-border attacks on coalition forces fighting growing insurgency in Afghanistan. (dpa)