ISLAMABAD: The head of Pakistan's Inter-Services Intelligence agency has postponed a visit to the United States due to “pressing commitments”, a military spokesman said Monday.

The postponement follows renewed tensions between the two countries over Pakistan's six-month blockade on Nato supplies into Afghanistan and last week's sentencing of a Pakistani doctor hired by the CIA to help find Osama bin Laden.

In a short statement sent to reporters by text message, the spokesman said that the visit by the ISI director general, Lieutenant General Zaheerul Islam, to the United States “has been postponed due to his pressing commitments here”.

“There is no other reason of postponing the visit,” the spokesman added.

Pakistani-US intelligence cooperation is understood to have continued despite stormy diplomatic relations between the two capitals, but frustration has been growing in both countries on how to break the stalemate.

Pakistani officials have reported five US drone strikes on Pakistani soil since a Nato summit last week, marking a dramatic increase in attacks that Pakistan demanded an end to after US air strikes in November killed 24 Pakistani soldiers.

The Chicago summit had been meant to symbolise a thaw between the United States and Pakistan, but appeared only to worsen the bad blood.

There is still no deal on reopening the Nato supply routes through Pakistan, vital for US and allied troops in Afghanistan.