TEL AVIV - Israeli Defense Minister Ehud Barak urged the Gaza Strip's Hamas rulers on Monday to rein in militant groups behind a surge in attacks on Israel, coupling his appeal with a veiled threat of Israeli action.

I think the recent days reflect the inability of Hamas to control the dissident groups, the Popular Committees or Islamic Jihad, who are trying to break the tranquility, Barak told Reuters during the unveiling of an Israeli anti-rocket system due to be deployed outside the Gaza Strip by June.

Hamas is well deterred from trying another direct collision with Israel. I hope that they will take over -- or else, Barak, asked if a new Gaza war was possible, said in English, referring to the Islamist movement imposing its authority on smaller armed groups.

On Sunday, three Palestinian militants were killed in an Israeli air strike in the Gaza Strip hours after Prime Minister Benjamin Netanyahu vowed a powerful response to any attacks from the territory.

Netanyahu said 20 mortar bombs and rockets had been fired at Israel from the Hamas-ruled territory last week.

Violence has risen along the Israeli-Gaza frontier in the past month, which could further complicate U.S.-backed diplomacy in the region, after a respite since a three-week Gaza war a year ago in which 1,400 Palestinians and 13 Israelis were killed.

Asked about Barak's comments, Hamas official Sami Abu Zuhri said the Palestinian attacks were carried out in response to continued Israeli aggression.

A Palestinian official, who asked not to be identified, said Hamas planned to meet other groups soon to urge restraint, unless Israel stepped up its attacks.

IRON DOME

Barak said Israel's new Iron Dome rocket interceptor system would change the equation and could deter militants from launching attacks.

It is a major change and provides the Israeli civilian population, once deployed in the coming years, cover against small-sized rockets and missilettes, he said.

The project was spurred by the 2006 war with Lebanese Hezbollah guerrillas, during which 4,000 rockets rained down on northern Israel.

On Thursday, three Palestinians were killed in a series of Israeli air strikes in Gaza, including the first air raid in months to target a site inside Gaza City.

Palestinians said the targets were sites belonging to other militant groups, not Hamas Islamists who seized the territory in 2007 and are seen as having reined in violence since the Israeli offensive last January.

Israel also dropped leaflets warning Gaza's 1.5 million residents to avoid coming within 300 meters (yards) of the border fence with Israel, citing security reasons.

(Writing by Jeffrey Heller in Jerusalem; editing by Andrew Dobbie)

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