Pakistan arrested 27 Indian fishermen and impounded their four boats on Saturday for allegedly fishing in its territorial waters in the Arabian Sea, a Pakistani maritime security official said.
Both India and Pakistan have carried out such arrests frequently, as the maritime border is poorly defined and many fishing boats lack the technology needed to be certain of their precise location.
The fishermen often languish in jail even after serving their term, as poor diplomatic ties between the two arch-rivals mean fulfilling official requirements can take a long time.
In August Pakistan released 163 Indian fishermen as an expression of goodwill. India often reciprocates such moves.
Muhammad Hassan Setho, a senior prison official, said there were 420 Indian fishermen in Karachi jail.
Relations between the neighbouring countries have worsened significantly since 2014, with shelling across the border in disputed Kashmir territory claiming a total of around 20 lives on both sides in August.
