Islamabad, May 11: Pakistan today imposed "reciprocal" restrictions on the movement of US diplomats after Washington took similar measures, a tit-for-tat move that is likely to further strain ties between the two countries.

Earlier, the restriction was to come into effect from May 1, but was deferred as the two sides decided to resolve the issue.

Foreign Office (FO) spokesman Dr Mohammad Faisal confirmed yesterday that the two sides would impose curbs on movement of each other's diplomats.

"The restrictions will be implemented from May 11 and on a reciprocal basis," he said, adding that "however, negotiations were going on between the two sides, on the matter."

According to the US decision, Pakistani diplomats, at the embassy in Washington and four consulates in New York, Los Angeles, Texas and Chicago, will need to stay within 25 miles (40-kms) of the city of their posting.

They would be required to take formal permission at least five day before moving beyond the prescribed limit.

Official sources said that the US has conveyed to Pakistan through a letter that the restrictions will be implemented today. The curbs are likely to further strain the ties already under stress due to multiple reasons, including the issue of immunity to US military attache Col Joseph Emanuel Hall who was involved in last month's fatal accident in which a motorcyclist had died after being hit by the US diplomat's vehicle here.

Pakistan has stopped Hall from leaving the country and demanded the US to withdraw his diplomatic immunity, so that legal action could be initiated against him.