More rain is expected in Pakistan as death tolls from the country's worst flooding in decades has reached 1,100.

Heavy thunderstorms and rains have been predicted throughout the country for this week as well as the possibility of a light to moderate monsoon moving in from India.

The storms mark the second week of heavy rain in Pakistan where flash floods and landslides have left more than 1,100 people dead and some 1 million affected, according to relief agencies.

The floods have hit hardest in the northwest region of the country, including the districts of Shangla and Swat, where officials say that massive damage has been done to bridges and other major infrastructure.

"Virtually no bridge has been left in Swat. All major and minor bridges have gone, destroyed completely," Major-General Athar Abbas told Reuters.

Relief workers also say there are now serious threats of water-borne diseases such as diarrhea an asthma being spread.

"We must prevent disease. There are already reports of stomach problems among children," Dr Mahmood Khan, a physician working with government teams in Peshawar and Nowshera, told IRIN.

Meanwhile, nearly 30,000 troops have been deployed by the government on rescue missions which have already saved some 19,000 people, according to authorities.

The U.S. embassy in Islamabad has contributed $10 million in immediate relief funds and has also provided rescue boats, helicopters, and other relief materials.

"The United States supports Pakistan's emergency relief efforts on behalf of people affected by recent monsoon floods," said the U.S. Ambassador to Pakistan Anne W. Patterson.

The United Nations, the ACT Alliance, and World Vision are also providing relief assistance.