Pakistani troops used helicopters and boats to evacuate thousands of marooned people from the country's plains where raging monsoon floods inundated more villages today.
In neighbouring India, the military dropped food for hundreds of thousands of people marooned in flood-hit areas of Indian-held Kashmir.
Pakistani and Indian officials said the death toll had reached 461 in the two countries.
Flash floods have washed away crops, damaged tens of thousands of homes and affected more than a million people since September 3, when heavy monsoon rains lashed Pakistan's eastern Punjab province and the Kashmir region, claimed by both India and Pakistan.
Ahmad Kamal, a spokesman for Pakistan's National Disaster Management Authority, said 261 people have been killed and 482 injured in Pakistan.
"The situation is still alarming as flood waters are entering the country's plains in the Jhang district, inundating more villages and affecting thousands," he said.
The military said it was expanding relief operations in Punjab, where the Chenab River overflowed. Troops in helicopters and boats evacuated 4,000 more people from Jhang, it said.
Mr Kamal said high floods were likely to reach the southern Sindh province later this week.
Authorities were supplying tents, food and other items to survivors, but many complained that the government was not doing enough.
"I feel as If I am a beggar, as I have to wait for hours to get free food," a survivor told a Pakistani news channel.
Hafiz Saeed, who heads Jamaat-ud-Dawa, an anti-India charity, accused India of releasing flood waters that caused destruction in Pakistan.
"Pakistan should take notice of this situation," he told a Pakistani news channel yesterday, adding that he was providing food to hundreds of thousands of flood victims in Jhang.
India says Jamaat-ud-Dawa is a front for Lashkar-e-Taiba, which it blames for a 2008 attack on the Indian city of Mumbai that killed 166 people.
Pakistan and India have a history of uneasy relations but relations have improved in recent years.
Each side has offered to help the other recover from the floods, the worst to hit Pakistan since 2010, when some 1,700 people died.
The Kashmir region in the northern Himalayas is divided between India and Pakistan and claimed by both.
Two of the three wars the countries have fought since their independence from Britain in 1947 have been over control of Kashmir.
In India, Sandeep Rai Rathore, head of the National Disaster Response Force, said today that 80 army and air force transport aircraft and helicopters were dropping drinking water, biscuits, baby food and food packets for hundreds of thousands of marooned people in the Indian-controlled portion of Kashmir.
Officials said the flooding has killed 200 people in India, where anger and resentment was mounting over what victims described as a slow rescue and relief effort.
"We want water and food. We will die here. Please drop some food packets," The Hindustan Times newspaper quoted S Lala, a stranded resident of Srinagar, as saying.
Eighty army medical teams were already operating in the region and have treated more than 10,000 patients.
Relief materials including 2,000 hospital bed sheets, blankets and tents, drinking water and cooked food were being airlifted to the region, the Indian government said in a statement.
In Srinagar, the main city in Indian-held Kashmir, most government hospitals and clinics were flooded and unable to treat patients.