Despite the heavy concerns of weapons smuggling by terrorists in Gaza, Israel is to extend the distance off the coast that fishermen in the Hamas enclave are allowed to operate from Sunday, their trade union said.

Fishing boats working out of ports in the southern part of Gaza will be allowed up to nine nautical miles off the coast, the chairman of the Gaza fishermen's union, Nizar Ayyash, said on Friday.

He said that the previous six mile limit would be retained in waters off the north of Gaza which neighbor those of Israel.

The Israeli defense ministry body responsible for implementing government policies in Palestinian controlled territories, COGAT, said on its Facebook page that ahead of the fishing season, the navy "decided to expand fishing south of Wadi Gaza from six to nine miles."

The wadi, or stream bed, reaches the Mediterranean just south of Gaza City.

COGAT estimated the decision could add 400,000 shekels ($106,000, 93,000 euros) a year to the Gazan economy.

Around 4,000 fishermen work in Gaza, more than half of whom live below the poverty line. The economy in Gaza has been crushed by the Hamas terror regime, which siphons off funds to build attack tunnels and missiles while largely neglecting and exploiting its population.

Hamas terrorists have fought three wars against Israel since 2008, including Operation Protective Edge in 2014.

Israel is imposing a legal naval blockade on the region to prevent the influx of weapons to the terrorists, and likewise Egypt has created a buffer zone on the border with Sinai to block smuggling.

AFP contributed to this report.