Pakistan's floods have caused "huge losses" to its crops, the country's food minister has told the BBC.
Nazar Muhammad Gondal said significant amounts of the grain, sugarcane and rice harvests had been washed away.
Meanwhile a senior religious scholar has said that flood victims living in difficult conditions should not have to fast over the Muslim Ramadan period.
And Pakistan's UK envoy has denied that most of the money given for flood defences has been lost to corruption.
High Commissioner to London Wajid Hasan dismissed the allegation by pressure group Transparency International, and insisted his government was doing all it could to help people in need.
Floodwater triggered by heavy monsoon rains is still surging south along the Indus River, forcing people from their homes.
Food Minister Gondal said grain stocks had been destroyed in Khyber Pakhtunkhwa (formerly North West Frontier) province, but some remained in southern Punjab province.
"We have losses in cotton, in sugarcane, in rice, in pulses and in tobacco - these are huge losses for the future," he told the BBC's World Today programme.
"These are the nation's cash crops which will really affect the economy of Pakistan."
Mohsin Leghari, a member of the Punjab regional assembly, told the World Today aid workers were being attacked by desperate, starving people.
"Their crops have gone, their livestock has gone, the infrastructure, the roads are gone," he said. "Right now our land link with the rest of the country is gone."
Mufti Muneebur Rehman, one of the country's top religious scholars, told the AP news agency that flood victims can perform their Ramadan fast later in the year.
The Ramadan period began on Thursday. Muslims throughout the country go without food from dawn to dusk each day for a month to control their desires and show empathy for the poor.
Meanwhile, a senior Islamabad envoy said recent comments by UK Prime Minister David Cameron about Pakistan "exporting terror" could deter the public from donating to the flood relief appeal.
Mr Cameron angered Islamabad during his visit last month to regional rival India, when he accused elements in Pakistan of looking both ways on militancy.
Pakistan's ambassador to the United Nations, Abdullah Hussain Haroon, told BBC's Radio 4: "Yes, indeed Pakistan has suffered because of what Mr Cameron has said, because the British people will listen to their prime minister."
Pakistan's meteorological service warned of floods in Hyderabad, Sindh province, and Kalabagh and Chashma in Punjab.
But forecasters also said the monsoon system should ease over the next three days.
The UN has launched an appeal for more than $450m (£290m) to help the 14 million Pakistanis affected by the floods. At least 1,600 people have died and many more are missing.
The US, which has already committed $55m to relief efforts, announced it was contributing another $16.2m to the UN refugee agency and the International Red Cross.
But in a statement this week, the Pakistani Taliban described the floods as God's punishment on the country for accepting secular leaders. They urged Pakistanis to boycott foreign aid.
BBC Urdu will transmit six daily bulletins in Urdu and Pashto providing vital information including how to stay safe, avoid disease and access aid. Special programmes will be broadcast each day in Urdu at 12.30, 15.30 and 18.30 and in Pashto at 12.45, 15.45 and 18.45 (local times).