International aid agencies have warned of potential outbreaks of cholera and other waterborne diseases after South Asia was battered by a week of torrential rain and heavy flooding.

Three million have been affected by the extreme weather in Pakistan and India, and more rain is expected across the region in the coming days.

An assessment by five relief agencies on Tuesday described a growing number of skin and stomach ailments among victims in Pakistan's Baluchistan province, which was hit by a tropical cyclone last week.

Many of the survivors have been living in the open and drinking polluted water from rivers after their homes were destroyed.

Cholera fears

"Some of the villages where we went yesterday had a bad smell. We learned a lot of livestock is buried under that mud. This is particularly dangerous because of the potential for it to lead to a cholera outbreak," Gul Wali Khan of Catholic Relief Services said in a statement.

The agencies planned to provide plastic sheets and bamboo poles for temporary shelter since tents were unsuitable in the extreme summer heat.

Heavy rains have disrupted road and rail traffic in India [AFP]

In neighbouring Sindh province, waters from the Qabbo Canal broke through protective embankments and inundated areas as far away as 26km, Anwar Haider, provincial relief commissioner, said.

Cases of diarrhoea, skin allergies and waterborne diseases were rising in the Qambar-Shahdadkot district of the province where the canal's waters had displaced some 30,000 people, he said.

Shaukat Aziz, Pakistan's prime minister, has asked for relief and rehabilitation aid from foreign countries, international agencies and private donors after a two-day tour of flooded regions.

He added that more helicopters would be added to army efforts to get food, medicine and other relief supplies to areas of Baluchistan province which was hit by Cyclone Yemyin last Tuesday.

India toll

In India, 44 more people were reported killed in torrential monsoon rains on Tuesday, taking the toll to 280, officials and media said.

The Press Trust of India said more than 7,000 people had been evacuated from low-lying areas in Gujarat state as the rains worsened, and 22 children had to be rescued when their school bus was surrounded by flood waters.

Heavy rain also lashed Mumbai, India's financial and entertainment capital, on Tuesday disrupting rail and road traffic.

Several schools and colleges were closed as low-lying areas in central and suburban Mumbai were flooded with knee-deep water.