India has accused Pakistan of reneging on a deal to free 240 Indian fishermen from its jails in a prisoner swap.
Hundreds have been freed by both sides since 2004
The fishermen were to have been freed along with 19 other Indians in a swap with 38 Pakistanis at the Wagah border point, India's foreign ministry says.
It said it had been told that 20 Indian fishermen were due to have reached Wagah - but their vehicle broke down.
Pakistan denied failing to honour commitments. The sides began prisoner swaps after peace moves in 2004.
The Indian Ministry of External Affairs said Friday's exchange had been agreed in May.
"We are disappointed to note that the 240 fishermen whose national status has already been confirmed were not released today despite the understanding," the statement said.
"We would like to reiterate that all 240 Indian fishermen should be released in accordance with the understanding of 31 May 2006.
"India is also awaiting consular access to 118 civilian prisoners and 192 fishermen and it is hoped that Pakistan will facilitate this by 31 July, in keeping with the understanding."
Pakistani officials said another 20 Indians were also scheduled to have been released, but gave no reason why they had not been handed over.
Pakistan's foreign ministry spokeswoman Tasnim Aslam said the 31 May accord applied equally to both countries and only 39 Indians fulfilled the criteria for release.
"How can they express disappointment when they are themselves doing the same? Why do they expect that Pakistan would make an exception? We would not," she told Reuters news agency.
The 38 Pakistanis and 19 Indians who crossed over at Wagah on Friday had all completed their prison terms, the BBC's Asit Jolly at Wagah says.
At talks a month ago the two sides decided to release all prisoners who had completed their terms and whose nationalities had been verified.
Hundreds have been arrested over the years on the wrong side of the border or for fishing in the wrong area.
Most of the Indians and Pakistanis languishing in each other's jails are poor farmers and fishermen - the two countries routinely detain each other's fishermen for straying into territorial waters.
A number of measures have been taken to improve bilateral relations since the peace process began.
However, movement still needs to be made on the key issue of Kashmir, which both nations claim in its entirety and over which the nations have fought two wars since independence in 1947.