JERUSALEM (AFP) - Israel's Foreign Minister Avigdor Lieberman said on Tuesday that military forces loyal to the regime of Syrian President Bashar al-Assad were behind a cross-border attack that killed an Israeli teenager.

"We received all the analyses and intelligence: it was clear that it was Syrian authorities," Mr Lieberman told public radio.

"Assad's forces fired at the Israeli civilian, on the vehicles that had stopped by the border, and they need to pay the price," he added.

The 13-year-old Arab Israeli, the son of a defence ministry contractor, was killed on the Golan Heights on Sunday when a missile hit the car he was in with his father.

The army said it was a deliberate attack against Israel, but was initially uncertain as to whether regime or opposition forces were behind it.

Israel responded immediately with tank fire, and hours later launched air strikes targeting Syrian military headquarters and positions.

Syria said the strikes killed four soldiers and wounded nine, and on Monday urged the United Nations to condemn Israel's "flagrant violation" of its territory.

Mr Lieberman said the Israeli reaction was "just how it should have been", and warned: "That's also how it will be in the future."

"I hope Damascus got the message," he added.

The Israeli army, meanwhile, said it was "observing the border very closely" and was "prepared for any development", but made no major changes in its deployment on the Syrian border.

"It seems that things are under control," army spokesman Peter Lerner told AFP.