The men were arrested more than a year ago, accused of entering Pakistani waters in an area of the Arabian Sea where the border is unclear.

India is also holding Pakistani fishermen for the same reason and Pakistan hopes its gesture - on the birthday of the nation's father, Muhammad Ali Jinnah, which coincides with Christmas Day - will be reciprocated.

"We have total of 518 Indian fishermen out of which 220 are being released today as a goodwill gesture of the Pakistan government. In the next phase, 219 fishermen will be released on January 5," Shunail Husain Shah, a police assistant superintendent, told Reuters.

Relations between the nuclear-armed neighbours have been more fraught than usual since a crackdown by Indian forces on dissent in Indian-controlled Kashmir began in July. In September militants killed 18 soldiers at an Indian army base, an attack New Delhi blamed on Pakistan.

"We appreciate Pakistan's goodwill gesture of releasing Indian fishermen, but we expect a similar reciprocal move by India, 156 Pakistani fishermen including 13 children are languishing in Indian jails," Muhammad Ali Shah, president of Pakistan Fisher Folk, a fishermen's rights body. told Reuters.

The UN Convention on the Law of the Sea states that fishermen who cross territorial waters can be warned and fined but not arrested, and Shah called on both countries to respect that.

One of the fishermen being released, who goes by the single name Naresh, told Reuters: "I am very happy, looking forward to meet my family back in Gujarat. We were treated nicely here, I will request the Indian government release the detained Pakistani fishermen as well."