GAZA CITY (Ma'an) -- Israeli naval forces on Thursday detained two fishermen off the northern Gaza coast, Gaza's Ministry of Agriculture said.

The men, from Beit Lahiya, were fishing north of Gaza City, the ministry said in a statement.

An Israeli military spokesman said a fishing boat deviated from the permitted fishing area designated by Israel.

The fishermen failed to respond to calls to return to the designated area and soldiers fired warning shots, confiscated the boat and detained the fishermen, the spokesman said.

The ministry said that fishing provides the sole source of income for many families in Beit Lahiya. It said there has been a recent increase in the number of fishermen detained by Israeli forces.

Israeli and Palestinian negotiators agreed on a 20-nautical-mile fishing zone off Gaza's coast under the Oslo Accords, but Israel unilaterally imposes a 3-mile limit. Israeli warships frequently open fire at boats that allegedly stray from the permitted area.

Fishermen say the limits have destroyed their livelihood and that it is impossible to trawl a large catch within the designated area.

Israel has controlled Gaza waters since its occupation of the area in 1967, and has kept several warships stationed off the coast since 2008.