Israeli army officials said the measure would compensate for Israel's loss of surveillance once it pulls out of the Gaza Strip later this year.

Palestinian negotiator Saeb Erekat condemned the planned sea barrier.

"I hope the Israeli mentality of barriers will end," he said, in a clear reference to the West Bank barrier, which is still under construction.

"Now they have land barriers and tomorrow sea barriers and the day after sky barriers - and what else?"

Israel says the construction of the West Bank barrier aims to stop suicide bombers, but the barrier often cuts a long way into occupied territory.

The BBC's Alan Johnston says the sea barrier will not stir up the same controversy as the West Bank barrier, because it will be built in Israeli territorial waters and not on occupied land.

Foiled attacks

According to the Jerusalem Post, the sea barrier's first 150m will consist of a concrete wall with its foundations buried in the sea bed.

A submerged 1.8m-deep (6ft) floating fence will stretch out for further 800m.

"It is (a system) to... prevent infiltrations of terrorists via the sea," Reuters quoted an anonymous Israeli security source as saying.

Israel is planning to pull all its 8,000 settlers from Gaza and the troops that protect them as part of a disengagement plan scheduled to begin in August. Israel will maintain control of Gaza's borders, coastline and airspace.

Four West Bank settlements are also to be evacuated.

A part of the pullout, Israel will also lose a naval base in southern Gaza where a vast surveillance system is based.

An electronic fence is already in place around the Gaza Strip. According to military officials, the construction of the sea barrier is due to start soon, but it will not be completed in time for the scheduled withdrawal.

In the past, Palestinian militants have made several attempts to swim in and attack Israeli settlements in Gaza, but they have always been stopped.