Pakistan has ordered the release of Indian fishermen in their custody, a day before India swears in right-wing Bharatiya Janata Party's Narendra Modi as its new prime minister, according to reports.

Authorities released 59 Indian fishermen from the Malir jail in Karachi and another 92 from Nara jail in Hyderabad in Sindh province, India's PTI news agency reported on Sunday.

Syed Nazir Hussain, the superintendent of the Malir jail in Karachi, told the agency that the Indian prisoners were released on the written directives of the interior and foreign ministries.

"Most of these prisoners are poor Indian fishermen who were arrested and brought here for trespassing into Pakistani territorial waters," he was quoted as saying by the New Delhi based agency.

India reciprocated by releasing more than 400 Pakistani fishermen from its jails, according to the Associated Press news agency.

Another neighbour, Sri Lanka, also announced release of five Indian fishermen.

"As a goodwill measure on the occasion of @narendramodi's swearing-in, President instructs officials to release Indian fishermen in custody," Sri Lanka's President Mahinda Rajapaksa tweeted on Sunday.

Positive gestures

This is the second time in the past two months that Sri Lanka has released Indian fishermen arrested for maritime trespassing and poaching.

The latest positive gestures from India's neighbours come as Pakistan's Prime Minister Nawaz Sharif and Sri Lanka's Rajapaksa are scheduled to attend Modi's oath taking ceremony along with other heads of SAARC countries.

Reports say Pakistan's prime minister will fly to India's capital, New Delhi, on Monday, accompanied by his National Security and Foreign Affairs Advisor Sartaj Aziz and Foreign Secretary Aizaz Chaudhry among others.

The decision by Sharif to attend Modi's inauguration, a first for the nuclear-armed rivals, could signal a further easing of the tensions.

Fishermen from each country languish in jails after accidentally crossing sea borders between India and Pakistan in the west and India and Sri Lanka in the south.

Most of them lack proper navigation tools and the waters are not divided by a physical boundary.

Obtaining their release is difficult and many are left in prison for years, because of long-running tensions between the countries.