Washington - US President Barack Obama said he was "gravely concerned" by the situation in Pakistan and expressed fears about the fragility of a civilian government struggling to contain the growing Taliban insurgency.

Obama said the Pakistani government lacked the ability to provide basic services for its people and promised the United States would do all it could to build up its institutions.

"I am gravely concerned about the situation in Pakistan," Obama said at a news conference at the White House. "The civilian government there right now is very fragile."

Taliban fighters have come within 100 kilometres of the capital Islamabad in recent weeks, prompting demands for greater military action by Western governments.

Obama said he would keep encouraging the Pakistani government to redirect its forces and efforts towards the Taliban in its north- western provinces and away from the border with India and its long- running conflict over Kashmir.

Despite the fears, Obama said he was confident the US could help ensure that Pakistan's nuclear weapons capability does not fall into the hands of extremists.

"I'm confident that we can make sure that Pakistan's nuclear arsenal is secure," Obama said. (dpa)