* Government has poor flood management record
* Tense ties with Washington
* Islamic charities step in to help flood victims (Adds comment from flood victim in Zardari's hometown)
By Augustine Anthony
ISLAMABAD, Sept 16 (Reuters) - Pakistani Prime Minister Yusuf Raza Gilani has cancelled a visit to the United States to attend the U.N. General Assembly session to direct relief efforts as floods devastate southern Pakistan, his office said on Friday.
President Asif Ali Zardari was widely criticised for trips to Britain and France last year when Pakistan was battling floods that killed about 2,000 people and made 11 million homeless and the government again stands accused of moving too slowly.
"The prime minister has cancelled his visit because of the floods and now the foreign minister will represent Pakistan on the visit," an official in Gilani's office told Reuters.
"The prime minister will visit flood-affected areas from tomorrow and supervise relief efforts."
The latest floods, triggered by monsoon rains, have killed more than 230 people, destroyed or damaged 1.2 million houses and flooded 4.5 million acres (1.8 million hectares) since late last month, officials and Western aid groups say.
More than 300,000 people have been moved to shelters. Some 800,000 families hit by last year's floods are still homeless.
Aid groups have warned of a growing risk of fatal diseases.
Last year, the military took charge of rescue and relief efforts, along with aid groups. The army is active again in the latest disaster. But some Pakistanis are growing impatient with it as well.
Juman and his extended family fled when water as high as 12 feet (3.6 metres) raged through their village. Home has been a thatched hut on a roadside for several weeks in another village called Mohammad Yusuf.
"We go to the army and we have been asking for food, but they beat us with sticks and told us to leave," said Juman, who added he was turned away because the army camp was already overwhelmed. "They scared us away."
ISLAMIC CHARITY OFFERS HELP
The military, which has ruled Pakistan for more than half of its history, is seen as the only institution that can handle crises in the nuclear-armed South Asian nation.
Pakistan's cash-strapped government already faces many challenges, from growing frustration over power cuts to a stubborn Taliban insurgency.
Disillusionment with the state can drive young men to join militant groups waging a violent campaign to topple the U.S.-backed government.
Some flood victims are turning to the Al Khidmat charity -- which is linked to the most influential Islamist party in Pakistan, Jamaat-e-Islami (JI).
JI is not believed to have ties with the Taliban or other banned groups. Nevertheless, its relief efforts in last year's floods and other natural disasters helped discredit the government because of its relative efficiency.
At a camp consisting of rows of white tents, green and blue JI flags flutter. Organisers wearing bright orange vests and badges organise flood victims, including one man who walked and waded through water with his cows for 46 kilometers (28 miles) after his village was destroyed.
People have to drink rain water and wash clothes in it but there is some relief.
"When we arrived there wasn't a camp here. They set the camp up and gave us the tents," said Shabira, 35, holding her baby. "Now we are getting food every day."
Gilani's decision to cancel his trip provided little comfort to distressed flood victims.
In Zardari's hometown of Nawabshah, some complained that workers used pumps to flush water away from the area around the president's house, while they were helpless.
"There is no one to care about us," said Zulfiqar Arain, a shop owner whose business has been shut.
"Ministers and government officials take media to places of their choice to mislead the nation into believing they are helping."
Pakistani leaders are facing pressure on the diplomatic front as well.
Islamabad's ties with Washington have been heavily strained since a unilateral U.S. raid killed Osama bin Laden in a Pakistani garrison town in May.
There were signs that ties were under repair when the allies recently spoke of counter-terrorism cooperation. But fresh tension has emerged.
A U.S. warning on militants based in Pakistan, blamed by Washington for this week's attack on the U.S. Embassy in Kabul, works against counter-terrorism cooperation between the two allies, the Pakistan Foreign Ministry said on Thursday.
It was referring to comments by U.S. Defense Secretary Leon Panetta that Washington would do whatever it takes to defend American forces in Afghanistan from Pakistan-based militants.
Gilani may have wanted to meet senior American officials on the sidelines of the U.N. General Assembly to try to patch up ties with Washington, the source of billions of dollars in aid.
Pakistani Foreign Minister Hina Rabbani Khar is expected to meet U.S. Secretary of State Hillary Clinton in the United States on Sept. 18. She will be addressing the General Assembly in Gilani's place. (Additional reporting by Rebecca Conway in Mohammad Yusuf and Hamid Sheikh in Nawabshah; Writing by Michael Georgy)