Bilateral ties between Washington and Islamabad are strained following a U.S. raid into Pakistan that resulted in the death of al-Qaida leader Osama bin Laden in May.
U.S. allegations the Pakistani intelligence agency has ties to the Haqqani network, blamed for a series of attacks in Afghanistan, have hurt the relationship even more.
British Foreign Secretary William Hague, addressing Pakistani delegates at a London conference, said ties with the British government remained strong.
"What happens in Pakistan matters to Britain and we will stand by Pakistan as it addresses the challenges it faces and build a durable relationship that we know will stand the test of time," Hague said.
Washington and Islamabad are engaged in a diplomatic spat over the Haqqani allegations. Pakistani officials had said they questioned Washington's commitment to joint counter-terrorism concerns. U.S. Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, told National Public Radio that the relationship with Pakistan was "very difficult" but, in general, joint initiatives in the region were "going well."
Hague noted that Pakistan was "vulnerable" to regional security threats "but it also has the potential to contribute significantly to its own security."