Israeli soldiers detained two sisters of Saleh al-Aruri, a top leader of Hamas who was killed in Lebanon this month, Palestinian sources and the Israeli army said on Sunday.
The killing of Aruri, the deputy chief of Hamas, in a suburb of Beirut on January 2 was widely attributed to an Israeli drone strike, fuelling fears that Israel's war in Gaza could widen into a regional conflict.
The Israeli army said on Sunday it had detained the two women in the occupied West Bank "after they incited to terrorism against the state of Israel", without elaborating, AFP reported.
The brother-in-law of Aruri, Awar al-Aruri, said the two women and several other family members had been put into "administrative detention".
The Palestinian Prisoners' Club, a campaign group, said Dalal al-Aruri, 52, and Fatima al-Aruri, 47, were arrested in separate locations near the city of Ramallah.
The Israeli army had accused Aruri of helping to plan the October 7 attack in southern Israel by Hamas fighters from Gaza.
Israel's military campaign in Gaza has since killed at least 23,843 people, mostly women and children, according to the Gaza health ministry.
The Palestinian Prisoners' Club said 5,875 Palestinians have been detained in the West Bank since the Gaza war began.
It said that, of these, 1,970 had been put under administrative detention, which allows for suspects to be held without charge or trial for renewable periods of up to six months.
Israel says administrative detention is intended to allow authorities to hold suspects while continuing to gather evidence, with the aim of preventing attacks or other security offences in the meantime.
Israel has occupied the West Bank since the 1967 Six-Day War and, excluding annexed east Jerusalem, the territory is now home to around 490,000 Israelis who live in settlements considered illegal under international law.