"It's still a very difficult situation and some areas which have been inaccessible because of damage to infrastructure remain largely inaccessible," Michael O'Brien, of the International Committee of the Red Cross and Red Crescent (ICRC) in Islamabad told RFI.
Although aid workers have begun to reach Baluchistan and Pakistan-administered Kashmir, many areas are still cut off by the record rainfall.
“Principally it's a question of infrastructure,” says O’Brien. “The damage in this kind of disaster is really quite enormous. There's also an imperative to get to people, including medical assistance, because of the circumstances in which people who have survived the flood are now living."
Water-borne disease is "high on the agenda for most humanitarian organisations", O’Brien says. The ICRC is focussing on prevention rather than treatment by handing out hygiene packs as part of relief supplies.
Villages and some towns in Punjab, the most populous province, are now under water, with only the tops of trees and upper floors of buildings visible in Kot Addu and Layyah in the south. The province is the country’s breadbasket and crops are under threat, leading the UN to warn of food shortages.
Weather forecasters predict more rain in Punjab and the southern Sindh province and say that rainfall is 25-30 per cent heavier than usual. Sindh is likely to experience its worst flooding in 34 years, according to the UN.
As anger grows over the government’s perceived failure to provide sufficient relief, a charity on the UN’s terror blacklist is active in rescue efforts. Jamaat-ud-Dawa, which is accused of being a front for the Lashkar-e-Taiba blamed for the 2008 Mumbai attacks, announced that it was sending 10 truck-loads of goods and nine medical teams to the worst-hit province, Khyber Pakhtukhwa.
"We have been let down very badly by Mr Zardari,” Sharif told journalists in Charsadda, one of the worst hit areas. “We have been let down more by him than the statement by David Cameron."