American nationals have been warned not to travel to a hill resort, north of the Pakistani capital, due to fears of sectarian violence, a United States Embassy official said on Wednesday.

The warning, issued on Tuesday, advised Americans against travelling to Murree, a hill town about 55 km north of Islamabad.

"There is new information indicating the potential for a sectarian attack in the city of Murree during the Pakistani Independence Day period, which culminates on August 14, 2005," a US Embassy spokesman said, quoting the travel advisory.

It advised Americans living in Murree to "restrict their movements to essential travel only." In 2002, four masked gunmen attacked a Christian school for the children of Protestant missionaries in Murree, killing six and wounding three others, all Pakistanis.

Six killed in attack on school in Pak

Pakistan, a former supporter of the Taliban, is a US ally in the war against terrorism. A US military operation ousted the Taliban from power in late 2001 for harbouring al-Qaida. President Pervez Musharraf [Images] angered Islamic radicals when he severed ties with the Taliban and became an ally with Washington.

Militants, some believed to be linked with al-Qaida, have been blamed for involvement in attacks on foreigners and sectarian violence in Pakistan since the September 11, 2001, attacks in the US.