The Israeli army made more arrests Friday of relatives of six escaped Palestinian prisoners, an advocacy body said, as troops kept up a massive manhunt in the occupied West Bank.

Israel has poured troops into the Palestinian territory since Monday's breakout by six militants from the high security Gilboa prison in northern Israel through a tunnel dug beneath a sink in a cell.

Two brothers and a sister of suspected mastermind Mahmud Ardah were arrested on Friday morning in the village of Arraba near Jenin in the northern West Bank, the Palestinian Prisoners Club said.

Ardah, a member of militant group Islamic Jihad, has been imprisoned for life since 1996 over his role in deadly attacks.

Other relatives of the six fugitives, all from the Jenin area, were arrested on Wednesday and are being held in detention, according to the Palestinian advocacy group.

The Israeli army had no immediate comment on the Friday arrests.

On Thursday, Public Security Minister Omer Bar Lev said he and Prime Minister Naftali Bennett had agreed to form a commission of inquiry led by a retired judge.

Palestinians have been celebrating the breakout with demonstrations in both the West Bank and the Israeli-blockaded Gaza Strip, some of which have been accompanied by rioting. More were scheduled for Friday.

An Israeli injunction is in effect against publishing details of the jailbreak investigation, even as Israeli media report on the scramble to recover from the embarrassing lapse.