Pakistani President Asif Ali Zardari has made his first visit to flood-hit areas of the country, following widespread criticism of his decision to travel abroad during the disaster.

The floods, triggered by monsoon rains, have killed at least 1,600 people and affected close to 14 million in the Khyber-Pakhtunkhwa, Punjab and Sindh provinces over the last two weeks. The U.N. has appealed for $460 million to provide immediate help, including food, shelter and clean water.

Mr. Zardari flew to the southern city of Sukkur in Sindh on Thursday and assured flood victims the government was working hard to provide relief.

The visit comes three days after he returned from a controversial trip to Europe.

Prime Minister Yousuf Raza Gilani traveled to flood-hit areas in the southwestern Baluchistan region Thursday and appealed for more international help.

Flood-Affected Areas

Two U.S. military helicopters were the first of 19 to arrive in Pakistan on Thursday from the U.S. amphibious assault ship USS Peleliu in the Arabian Sea. The aircraft will help with relief efforts and replace six combat helicopters from the U.S. war effort in neighboring Afghanistan.

U.S. Defense Secretary Robert Gates ordered the 19 helicopters to Pakistan on Wednesday. The U.S. embassy in Islamabad says the U.S. military has helped rescue more than 3,000 people and transported 146,000 kilograms of emergency supplies since August 5.

Pakistani Ambassador to the United Nations Abdullah Hussain Haroon on Wednesday called the floods a "horrendous disaster," saying they have affected 150,000 square kilometers of land and wiped out 4,700 villages.

Hundreds of homes, bridges and roads have been washed away, with at least two million left homeless.

U.N. officials say high levels of gastroenteritis and diarrhea have already been found among flood victims.

Some information for this report was provided by AP, AFP and Reuters.