Israel put two more alleged Jewish extremists in a controversial form of detention without trial on Sunday after calls for a crackdown following the deadly firebombing of a Palestinian home, the defence ministry said.

"Meir Ettinger and Eviatar Slonim, who were arrested in recent days, have been placed in administrative detention for six months with the possibility of extension," a defence ministry spokesman told AFP.

A third alleged Jewish extremist, Mordechai Mayer, had already been placed in administrative detention, a measure usually reserved for Palestinians.