The United Nations is warning that the flood crisis in Pakistan is far from over, as rivers threaten to burst their banks in the southern Sindh province.
The floods in Pakistan have left an estimated 1,600 dead and affected at least 14 million people, the UN says.
Notes from the field:
"This has been a slow-motion catastrophe," the CBC’s Adrienne Arsenault said from Islamabad.
"That means that the needs are always changing, the location is always changing, the gravity of the problem is always changing."
Arsenault said military relief flights in the northern stretch of the country were delayed Thursday because of wind and rain.
In the south, damaged communications systems slowed efforts by rescue crews to get in touch with people marooned by the floods.
"The aid agencies are worried," Arsenault said. "There are some villages that have had absolutely no contact with rescuers in nearly two weeks."
The floods were triggered more than two weeks ago by torrential downpours, beginning in the northwest before spreading south and inundating thousands of villages. More rain is forecast in the coming days, and large areas of Punjab and Sindh provinces are still on flood alert.
Prime Minister Yousuf Raza Gilani flew over parts of Punjab, Sindh and Baluchistan provinces with an Associated Press reporter. Seen from the air, the extent of the disaster was clear, with the aircraft often flying for many minutes over a mostly flooded landscape.
"All I say is that we need more help from our international friends," he said. "We need more such helicopters because [of] the magnitude of the destruction."
"I also urge my own countrymen and women to help their brothers and sisters," he said.
Meanwhile, Pakistani President Asif Ali Zardari, who has faced an onslaught of criticism over the government's flood response, made his first visit to victims of the disaster on Thursday, according to state-run Pakistan Television.
A presidential spokesman told the BBC that the president visited a relief camp and spoke with flood victims in Sukkur city, on the banks of the swollen Indus River.
Government officials and relief agencies have struggled to deliver aid after flood waters washed away bridges and roads.
Heavy rain and swollen rivers have also washed away crops and contaminated local water supplies, causing a spike in food prices and concerns about access to clean water in many communities.
"There could be a second wave of deaths due to water-borne diseases if we don't act fast enough to provide safe drinking water," UN humanitarian affairs spokesman Maurizio Giuliano told the IRIN news agency.
UN appeals for aid
The UN launched an international appeal on Wednesday for nearly half a billion dollars in emergency aid to provide food, clean water, shelter and medical care over the next three months.
How you can help
To donate to Pakistan flood relief efforts, visit:
"It is clear that this disaster is one of the most challenging that anyone has faced in recent years," said John Holmes, a UN emergency relief co-ordinator.
The U.S. has committed more than $70 million, while the U.K. has pledged $30 million. So far Canada has only promised $2 million, prompting some criticism.
David Leipert, from the Muslim Council of Calgary, told CBC News that Canada should come through for Pakistani flood victims in the same way it came through for Haitian earthquake victims.
"Our economy is one of the strongest economies in the world," he said. "Our government should step up with a significant percentage."
Aid agencies fear that help may be slow in coming because the full extent of the disaster has yet to be seen.