Pakistani President Asif Ali Zardari returned home on Tuesday from official foreign visits to a chorus of criticism over his government's response to the country's worst flooding in 80 years.

The floods, triggered by unusually heavy monsoon rain over the upper Indus river basin that started nearly two weeks ago, have ploughed a swathe of destruction more than 1,000 km (600 miles) long from northern Pakistan to the south, killing more than 1,600 people.   

Poor weather has grounded relief helicopters and fresh rains have compounded the misery of more than 13 million people -- about 8 percent of the population -- whose lives have been disrupted by the floods, including two million homeless.

Zardari, the widower of assassinated former prime minister Benazir Bhutto and whose rule has been mired in controversy, enraged his critics by going ahead with state visits to Britain and France as the catastrophe was unfolding.

The military has taken the lead in relief efforts while the government is under fire for perceived neglect.

"The president has returned and he is in Karachi. He will come to Islamabad today," Zardari's spokesman Farhatullah Babar told Reuters. A government official said he was expected to visit the flood-hit areas within days, but for many Pakistanis, his trip is too little, too late.

"All that I can say about Zardari is that our houses are collapsing and his government is not even bothered," said Daraz Gul, a salesman in a hardware market in the town of Nowshera in northwest Pakistan.   

"A government is supposed to be like a parent. If a parent leaves his children in trouble and goes on jaunts abroad, it is scandalous."    

Dozens of protesters in the southern town of Sukkur in Sindh also accused politicians of ignoring flood victims. "They want to save their own lands and factories. They don't care if Sukkur is drowned," said cloth merchant Salahuddin Ahmed.   

Zardari has been a ceremonial president since parliament adopted constitutional changes stripping him of his powers this year, and the government, led by his political party, said it was was dealing with the floods and the issue should not be politicised.

US officials are concerned about the damage caused by the weak government response to the floods and mounting hostility toward Zardari. Pakistan is a key US ally whose help Washington needs to end a nine-year Taliban insurgency in Afghanistan.

The United Nations says in terms of the number of people who have lost their homes or livelihoods, and will need short- or long-term help, the floods were worse than the 2004 tsunami, which killed 236,000 people around the Indian Ocean.

UN Secretary-General Ban Ki-moon told reporters in New York that he was "extremely concerned" about the situation. "We will soon issue an emergency response plan and an appeal for several hundred million dollars to respond to immediate needs," he said.

The International Monetary Fund said on Monday the disaster will cause "major harm" to the economy, as donors' and investors' concern grew over the disaster's impact on an already fragile economy.

In India, some 300 people remained missing on Monday from floods last week's floods triggered by heavy rains in the Himalayan region of Ladakh that borders Pakistan. The floods have killed 156 people. - Reuters