A day after New Delhi suggested that Islamabad had not kept its word on prisoner exchange, Pakistan on Saturday gave a new twist to the issue, saying the 240 Indian fishermen due to be released on Friday, would be set free only after they complete their sentences for entering Pakistani territorial waters.

"It is not enough that their national identity has been established. They entered our waters deliberately for poaching purposes and have to complete their sentences," Pakistan Foreign Office spokesperson Tasnim Aslam told PTI in Islamabad.

She was reacting to an External Affairs Ministry statement which said that India was "disappointed to note that the 240 fishermen whose national status has already been confirmed were not released" on Friday "despite the understanding between the Indian home secretary and Pakistani interior secretary."

Aslam said they needed to undergo sentence to deter them from returning.

"How will you deter them," she asked and referred to 30 of Pakistani fishermen in Indian jails, apparently wanting them also to be released simultaneously.

New Delhi has said that they were nabbed in the first week of June and would be provided consular access on July 13.

Asked about the duration of the sentence the fishermen would have to undergo, Aslam said she would have to verify the details.

Pakistan at present has 432 Indian fishermen in its prisons, out of which the national status of 240 has been established.