Pakistan has arrested 12 Indian fishermen who had mistakenly crossed over to its territorial waters off the Karachi coast.

Maritime Security officials said that five fishing boats had also been impounded and the fishermen have been handed over to the dock police.

"Maritime Security Agency ship Nusrat has apprehended five Indian fishing boats along with 12 crew members onboard on March 2 for fishing illegally in Pakistani waters," a statement by Pakistan Maritime Security Agency, said on Saturday.

The ship was on routine patrol in the Eastern Maritime Region when it found these boats fishing illegally around 23 nautical miles inside Exclusive Economic Zone (EEZ) of Pakistan, it said.

Commander Zakir, an official of the Pakistan Maritime Security Agency said the Indian fishermen had been arrested around 50 kilometres inside Pakistan's economic zone.

Indian officials in Karachi said nearly 380 Indian fishermen languished in Pakistan jails despite periodic releases. Since last year Pakistan has been releasing only the captured fishermen and not their boats. As a result, several hundreds boats of the Indian fishermen continued to be in the possession of Pakistan authorities.