Israeli naval gunfire wounded a fisherman off the coast of Gaza on Thursday, a medical official said, in a sign of ongoing tension around the battered Palestinian territory.

The man was moderately wounded in the incident, emergency services spokesman Ashraf al-Qudra told AFP, without providing further details.

Israel's military had no immediate confirmation of the incident.

Shortly afterwards, air raid sirens sounded in southern Israel in what was later declared to be a false alarm.

The two incidents illustrated ongoing tensions in and around the enclave just three weeks after a fragile truce ended a bloody 50-day conflict between Gaza militants and Israel.

The international community has warned that without concerted efforts to rebuild the decimated Gaza Strip, violence could erupt again, possibly in a matter of months.

The World Bank and the IMF on Tuesday urged Israel to alleviate its eight-year blockade on Gaza in order to allow economic recovery, after a vast number of homes and infrastructure were destroyed in the fighting.

The war cost more than 2,140 Palestinian lives, and those of 73 people on the Israeli side.

Israel agreed as part of the August 26 truce to allow Gazan fishing boats to venture up to six nautical miles offshore, with a view to extending that to 12 miles.