Jerusalem (AFP) - A second suspected Jewish extremist was arrested Tuesday in Israel following the firebombing of a Palestinian home that burned a baby alive, the Shin Bet internal security force said.

Israel on Monday arrested Meir Ettinger, whose grandfather Meir Kahane founded the racist anti-Arab Kach group, and a court prolonged his detention until the weekend on suspicion of "nationalist crimes".

"A second individual, Eviatar Slonim, was arrested for belonging to an extremist organisation," a Shin Bet spokeswoman told AFP, without providing details on any charges against him.

Israeli television reported that the office of Attorney General Yehuda Weinstein had given permission for authorities to place three suspected Jewish extremists in "administrative detention".

The measure would need the green light from Defence Minister Moshe Yaalon, it added.

Media reports said Ettinger could face a year of such detention under the government's harder line against "Jewish terrorists".

Israel normally applies the measure, which dates from British-mandated Palestine, against Palestinians, allowing renewable six-month periods of detention without trial.

Currently, 379 of the 5,686 Palestinian prisoners held in Israeli jail are on administrative detention, according to official figures.

Friday's attack in the occupied West Bank, which killed 18-month-old Ali Saad Dawabsha, sparked an international outcry over Israel's failure to get to grips with violence by hardline Jewish settlers.