More than 600 have been killed across South Asia as the annual summer monsoon brings downpours and extreme weather, with at least 117 deaths in southwestern Pakistan during the past week.

Swathes of the normally desert Pakistani province of Baluchistan remain under water following the impact of Cyclone Yemyin last Tuesday plus heavy weekend monsoon rains.

Foreign Office spokeswoman Tasnim Aslam said Pakistan had not sought international help but that the UN had offered helicopters and medicines.

"We have been approached by a number of countries, the UN particularly, regarding the kind of assistance that we require in the relief efforts," Aslam told a weekly briefing.

The last time Pakistan needed international aid was during the October 2005 South Asian earthquake, which killed 73,000 people and left more than three million homeless.

Helicopters were still plucking cyclone survivors from their rooftops or dropping food to cut-off mud-brick villages on Monday, while other victims are living in camps, television footage showed.

Prime Minister Shaukat Aziz was quoted by state media after a trip to the disaster zone on Sunday as inviting international agencies and foreign countries to help the relief effort.

Provincial relief commissioner Khuda Bakhsh Baloch said flash floods at the weekend in Baluchistan's Khuzdar area killed at least 35 people, while other bodies had been found, bringing the toll for the week to at least 110.

More than 200,000 are homeless while 1.5 million were affected, he said.