LONDON: US Secretary of State Hillary Clinton said Thursday that Pakistan was too important for Washington to turn its back on, following ice-breaking talks with her Pakistani counterpart.

Clinton and Hina Rabbani Khar spoke for an hour and a half on the sidelines of a London conference on Somalia, in a first step towards thawing relations that were frozen in November when US air strikes killed 24 Pakistani soldiers.

Clinton said there would still be "ups and downs" in the relationship but that neither side could afford to shun the other.

"Building and sustaining a relationship based on mutual interest and mutual respect takes constant care and work, from both sides," Clinton told a press conference.

"I'm sure we will continue to have our ups and downs. But this relationship is simply too important to turn our back on -- for both nations.

"And we both remain committed to continue working to improve understanding and cooperation."

Relations between Pakistan and the United States were severely damaged last year by a covert American raid that killed terror chief Osama bin Laden, as well as the air strikes on the soldiers.

Clinton and Khar discussed tackling violent extremism, supporting Afghan-led reconciliation and improving ties between Washington and Islamabad, the secretary of state said.

She spoke of "difficult times which I admit we are in", adding that there had been "a lot of swirling in the air of who said what when that does not accurately reflect the state of the relationship".

The meeting was an important chance to "keep the lines of communication open" and "the work hasn't stopped", she added.

The United States says Pakistan's tribal belt provides sanctuary to Taliban fighting in Afghanistan, Al-Qaeda groups plotting attacks on the West, Pakistani Taliban who routinely bomb Pakistan and other foreign fighters.

President Barack Obama last month confirmed for the first time that US drones target Taliban and Al-Qaeda militants on Pakistani soil, but American officials do not discuss details of the covert programme.

The US strikes are deeply unpopular among the Pakistani public, who see the attacks as a violation of sovereignty and who blame the government's US alliance for much of the violence plaguing the country.