JERUSALEM, Nov 16: A submarine from a Western country slipped into Israeli waters last week on a spy mission, evading missile boats scrambled to intercept it, military sources said on Monday.

The sources did not name the country that sent the submarine, which penetrated five kilometres into territorial waters off Israel's northern Mediterranean coast, or say how long the vessel had been in the area.

The incident occurred on Nov 10, three days after the Hezbollah group breached Israeli air defences by sending an unmanned spy plane over the northern city of Nahariya.

The Hezbollah said such drones could be armed in the future to attack targets inside the Jewish state. There was no apparent connection with the submarine incident.

"It was a Western submarine which came seeking intelligence information," one military source said. "Once it was identified as such, missile boats were called in but it managed to escape."

Yuval Shteinitz, chairman of parliament's foreign affairs and defence committee, praised the navy for discovering the submarine following the air force's failure to detect the drone.

Shteinitz said the Israeli gunboats took action that signalled to the submarine that it was in their sights and the unidentified vessel left the coastal area.

"The submarine...was detected immediately with its entry into territorial waters and then was gotten rid of," he said.

Israel's territorial waters stretch 12 to 14 nautical miles off of its Mediterranean coast.

Israeli radio reports said the incident prompted the navy to place all of its ships and radar systems on high alert, and that similar incidents occurred in the past but were not publicised.

Israeli security sources said it was unlikely the submarine had entered Israeli waters by accident.-Reuters