Pakistan's nuclear sites and military installations remained safe and free from danger during the worst of the flooding to hit the country, the military said Thursday.

"There is no danger to our defence and nuclear installations from flooding," military spokesman Major General Athar Abbas told AFP.

"All our nuclear and military installations have remained safe and there is no further danger from flooding," Abbas added.

Pakistan has a 325-megawatt Chinese-built nuclear power plant at Chashma, in south of Punjab province, and another being built on the left of the Indus river, which burst its banks.

Weather forecasters signalled that the monsoon systems may ease off after three weeks of torrential rains triggered the devastating floods that have left nearly 1,500 people dead in Pakistan's worst natural disaster.

The floods wiped out villages, farmland and infrastructure, and the UN aid coordination body OCHA said that more than 650,000 homeless families were still without basic shelter.

Pakistan's nuclear sites also remained safe after 7.6 magnitude earthquake in 2005 which killed more than 73,000 people.

Pakistan tested its nuclear device in May 1998, after South Asian rival India conducted its nuclear tests.

There have been concerns in the West about the safety of Pakistan's nuclear arsenal from Islamist extremists.

The United States is reported to have set up an elite squad that would attempt to secure its weapons if the government ever disintegrated.