Israel has deployed drones to keep watch on gas fields off its northern coast, fearing attack by the Hezbollah militia from neighbouring Lebanon, the Jerusalem Post daily reported on Tuesday.

The fields lie in a part of the Mediterranean that is claimed by Israel for gas exploration and production, but Lebanon says the fields lie within its territorial waters.

"The decision to deploy drones was made in order to maintain a 24-hour presence over the site," the paper said, adding that the air force was equipped with the locally made Heron drone, which has special electro-optics designed for maritime work.

The Israeli military would not confirm or deny the Post report to AFP.

The paper said that the air force started aerial surveillance after a warning last month from Hezbollah, which in 2006 fought a deadly war with the Jewish state in which it used anti-ship missiles.

"The Israeli enemy cannot drill a single metre in these waters to search for gas and oil if the zone is disputed... No company can carry out prospecting work in waters whose sovereignty is contested," the Shiite group said.

The Hezbollah threat came after Israel's cabinet approved a map of the country's proposed maritime borders with Lebanon and submitted it to the United Nations, which has been asked to mediate in the dispute.

The map conflicts with one submitted by Lebanon to the UN last year, which gives Israel less territory.

The two countries are technically at war and will not negotiate face to face.

The disputed zone consists of about 854 square kilometres (330 square miles).

The two biggest known offshore fields, Tamar and Leviathan, lie respectively about 80 kilometres (50 miles) and 130 kilometres (81 miles) off Israel's northern city of Haifa.

Tamar is believed to hold at least 8.4 trillion cubic feet of gas (238 billion cubic metres), while Leviathan is believed to have reserves of 16 trillion cubic feet (450 billion cubic metres).

In June an Israeli company announced the discovery of two new natural gas fields, Sarah and Mira, around 70 kilometres (45 miles) off the city of Hadera further south.