A Palestinian fisherman has been killed after the Israeli navy opened fire on a vessel it accused of breaching the blockade north of the Gaza Strip.

Nizar Ayash, the Palestinian fishermen's union chief, said Monday's shooting and the arrest of four other crew happened in one incident, and two more arrests were made when the military boarded another Gaza boat overnight.

An Israeli military spokesperson confirmed the shooting.

"A vessel deviated from the designated fishing zone in the northern Gaza Strip," she told AFP news agency.

"Naval forces in the area called upon the vessel to halt and fired warning shots into the air."

She said the boat ignored the warning and the navy then opened fire.

The dead man's family identified him as Mohammed Bakr, 25. His body was transferred to a morgue in Gaza ahead of his funeral later on Monday.

Bakr's death came as Palestinians throughout the occupied territories, Israel and the world held rallies to commemorate the 69th anniversary of the Nakba.

The Nakba, or the Day of the Catastrophe, marks the expulsion of more than 750,000 Palestinians from their homes, the destruction of more than 500 villages and towns, and the creation of the state of Israel.

Fishing off the northern part of the territory adjacent to Israel is limited to six nautical miles offshore and the Israeli navy regularly fires at Palestinians at the zone's outer limit.

Such incidents rarely result in deaths, however.

The Gaza-based Palestinian Centre for Human Rights said several boats were chased in separate incidents over the past 24 hours.

Israeli blockade

Israel and Palestinians in Gaza have fought three wars since 2008 and the territory has been under an Israeli blockade for 10 years.

The Israeli military says it patrols Gaza's waters to prevent the smuggling of weapons into the territory and to stop attacks.

READ MORE: Who killed Gaza's fisherman Muhammad al-Hissi?

UN officials have called for the blockade to be lifted, citing deteriorating humanitarian conditions, but Israel says it is needed to keep Hamas, which runs the strip, from importing weapons or materials used to make them.

In 2016, Israel detained at least 70 Gaza fishermen who had strayed beyond the border, a senior naval commander said.

About 4,000 fishermen work off the coast, more than half of whom live below the poverty line.