In a goodwill gesture ahead of External Affairs Minister Pranab Mukherjee's visit to Islamabad this week, Pakistan on Tuesday released 115 Indian fishermen held in a Karachi prison for nearly two years.

The fishermen, detained for illegally fishing in Pakistani waters, were released from Karachi's Landhi jail after a brief ceremony, and would be formally handed over to Indian authorities at Wagah border on Wednesday.

The Pakistan government, however, declined to release their boats as a punishment measure to deter them from crossing into Pakistani waters again.

Pakistan released 70 Indian prisoners from Karachi and Lahore last month with 50 of them arrested for illegally crossing Pakistan's territorial waters.

Pakistan still has 347 fishermen lodged in its various prisons. It was not clear when they will be released.

Every year about 1,000 Indian fishermen, mostly from Gujarat, are detained by Pakistani authorities for straying across to its territorial waters.

Pakistani fishermen too get caught by the Indian Coast Guard for the same reason.

Mukherjee is scheduled to visit Pakistan for two days beginning January 13 to extend an invitation to the Pakistani leadership for the forthcoming South Asian Association fore Regional Cooperation summit to be held in New Delhi, and review the third round of composite dialogue process with his Pakistani counterpart Khurshid M Kasuri.