ISLAMABAD — The wall of floodwater that's rushing through Pakistan devastated new areas Thursday, reaching the most heavily populated parts of the country, officials and aid workers said.
The raging waters, caused by torrential rain in the north of the country, have rushed down the Indus River and inundated parts of southern Punjab province, which is home to half of the country's 170 million people. Mass evacuations began farther downriver in Sindh, which contains Karachi, Pakistan's largest city.
The United Nations estimated that more than 4 million people have been affected so far by the country's worst flooding in more than 80 years, which has washed away homes, roads and crops. Parts of southern Punjab were described Thursday as a giant lake. The death toll is more than 1,600, but the precise figure is unknown.
The flooding also threatens to erode support for Pakistani President Asif Ali Zardari, whom the Obama administration considers a key ally in the war on militant Islamist groups in Pakistan and neighboring Afghanistan. In some areas, militant groups have moved to fill the vacuum left by the government's halting efforts to assist flood victims.
In Punjab, Pakistan's political nerve center, the provincial government is run by the Pakistan Muslim League (N), the country's main opposition party, led by former Prime Minister Nawaz Sharif. He's using the crisis to score points while Zardari refuses to cut short a much-criticized trip to Britain and France, trailed by a large entourage.
There are indications that the government in Punjab, which has had more time to prepare than other regions have, is handling the crisis better than the northwestern province of Khyber Pakhtunkhwa, which was overwhelmed.
Punjab, however, is also the country's agricultural hub, and more than a million acres of crops there have been destroyed, raising fears of food shortages.
"The body of water going south is affecting a large area that is highly densely populated. It is the food basket of Pakistan, so it will have long-term effects," said Oscar Butragueno of UNICEF.
To the south in Sindh, 350,000 people were moved from their homes in low-lying areas near the Indus River as the authorities issued a flood alert. The surging waters now threaten two key dikes, at Guddu on the Punjab-Sindh boundary and a huge colonial-era barrier at Sukkar, just inside Sindh.
"The waters are reaching Sindh just now," said Maurizio Giuliano, a spokesman for the U.N.'s emergency relief arm, the Office for the Coordination of Humanitarian Affairs. "There is a risk that the barrages (dikes) will be breached. This is already a major disaster, but if that were to happen, it would lead to a serious deterioration of the situation."
On Thursday, Kot Adu, a town in southern Punjab, was totally submerged, with almost its entire population of 300,000 residents evacuated, said Uzma Shafi, an aid worker with Plan International, a British-based charity. People escaped with their loved ones and also with their livestock, valuable possessions but ones that caused more chaos.
Regarding the aid effort, "Things are better in the last few days. I am impressed," said Daud Saqlain, a worker with ActionAid, another British charity, speaking from Layyah in southern Punjab. "One big problem is that people do not heed the advance warnings to evacuate. Only once the waters come into their homes do they get out."
The U.N. estimates that 1.4 million people in Punjab have been affected by the floods, with 74,000 homes severely damaged or destroyed. Across the flood zone, more than 250,000 homes have been lost or severely damaged.
Soldiers have taken up much of the relief work. The Pakistani military said that it had rescued 75,000 stranded people so far, by boat and helicopter.
The U.S. military also has become involved. Four U.S. Army helicopters flew relief missions in northwest Pakistan on Thursday, according to the American Embassy in Islamabad.
(Shah is a McClatchy special correspondent.)
MORE FROM MCCLATCHY
U.N.-listed 'terror front' group leads flood relief in Pakistan
As Pakistani government falters after flooding, Islamists fill void
Pakistan frees head of militant group accused of Mumbai attack
