KABUL: Defense Secretary Leon Panetta said on Thursday the United States was reaching the limits of its patience with Pakistan because of the safe havens the country offered to insurgents in neighbouring Afghanistan.
It was some of the strongest language used by a US official to describe the strained ties between Washington and Islamabad.
Panetta was speaking in the Afghan capital, where he arrived for talks with military leaders amid rising violence in the war against the Taliban and a spate of deadly incidents, including a NATO air strike said to have killed 18 villagers.
The United States has long pushed Pakistan to do more to help in the war against militancy, but the relationship has received a series of blows, not least by a unilateral US raid into Pakistan to kill Osama bin Laden last year which humiliated Islamabad.
"It is difficult to achieve peace in Afghanistan as long as there is safe haven for terrorists in Pakistan," Panetta, who arrived in Kabul a day after a deadly insurgent bombing, told reporters.
"It is very important for Pakistan to take steps. It is an increasing concern, the issue of safe haven, and we are reaching the limits of our patience."
Pakistan's cooperation is considered critical to US efforts to stabilise Afghanistan before most foreign combat troops leave at the end of 2014. Pakistan has strong traditional links with the Afghan Taliban and other militant groups.
A Pakistani doctor accused of helping the CIA find bin Laden has been jailed for 33 years for treason last month, officials said, deepening strains in ties between Washington and Islamabad.
Pakistan's parliament has been drawing up recommendations on how to proceed on ties with Washington, including a halt to US drone strikes in the country that have enraged many Pakistanis.
Afghan President Hamid Karzai said on Thursday he was cutting short an official visit to China following reports of civilian deaths in a NATO air strike in southeast Afghanistan and an insurgent bombing in the south, the presidential palace said.
Karzai said 18 civilians were killed in a pre-dawn air strike in Logar province on Wednesday. The NATO-led International Security Assistance Force said it was investigating.