The US-backed government, overwhelmed by one of the worst natural disasters in Pakistan's history, already faces renewed Taleban violence.

"Unfortunately the flooding in Pakistan is probably going to delay any operations by the Pakistani Army in North Waziristan for some period of time," US Defense Secretary Robert Gates said in Afghanistan where he is visiting US troops.

Aside from its struggles against homegrown Taleban, Pakistan is under intense American pressure to tackle Afghan Taleban fighters who cross the border to attack US-led NATO troops.

Pakistan has said it will decide to carry out an assault in North Waziristan, where Washington says anti-American militants enjoy safe havens, at the time it considers appropriate.

Attention has focused on the Pakistani Taleban again after US prosecutors charged its leader, Hakimullah Mehsud, in the plot that killed seven CIA employees at an American base in Afghanistan last December.

Mehsud, believed to be hiding in the tribal areas of Pakistan, was charged with conspiracy to kill Americans overseas and conspiracy to use a weapon of mass destruction.

The Lahore attacks, which involved suicide bombers, suggest the Taleban are trying to hit the government as it struggles to cope with the floods, which have made millions homeless, destroyed infrastructure and crops and hammered the economy.

Charities, some of them linked to militant groups, have at the same time joined in the relief effort for the millions affected by the worst floods in the nation's history.

US officials are concerned that the involvement of hard-line groups in flood relief will undermine the fight against militancy in Pakistan as well Afghanistan.

Pakistan is now expected to come under more US pressure to stamp out homegrown militants, raising the possibility it will have to pour more resources into that campaign as it tries to avoid an economic catastrophe caused by the floods.

Some relief has come from the International Monetary Fund (IMF). It will give Pakistan $450 million in emergency flood aid and disburse funds in September to help the country's economy cope with the devastation of the floods.

The flooding has destroyed cropland and livestock and displaced millions of people, causing damage the government has estimated at $43 billion, or almost one quarter of the South Asian nation's 2009 GDP.

Talks in Washington with a delegation led by Pakistan's Finance Minister Abdul Hafeez Shaikh on the terms of an $11 billion IMF loan program left him satisfied with the country's commitment to reforms, the IMF chief said.

Under the 2008 IMF loan program, Islamabad pledged to implement tax and energy sector reforms and give full autonomy to the State Bank of Pakistan.