HEBRON West Bank (Reuters) - Israeli troops killed a Palestinian teenager in the occupied West Bank on Friday and arrested 25 people, pursuing a crackdown on Islamist militants and house-to-house searches for three Israeli teenagers who went missing eight days ago.

Israeli soldiers take part in an operation to locate three Israeli teens in the West Bank City of Hebron June 20, 2014. REUTERS/Mussa Qawasma

Palestinian medics said Mohammed Dudin, 15, was killed in the village of Dura, near the city of Hebron in the West Bank. The Israeli military said troops had fired live ammunition when rocks and firebombs were thrown at them during an arrest raid.

Thousands attended a funeral in Dudin’s hometown and Palestinian police dispersed a protest by some 200 women and men in Hebron demanding that Israel release Palestinian prisoners held in its jails.

Israel said it arrested 25 people overnight in towns, refugee camps and cities across the West Bank, bringing the total number of detainees to 330 including 240 from Hamas, the Islamist group Israel accuses of kidnapping the three teenagers who vanished near a Jewish settlement on June 13.

Hamas, which advocates Israel’s destruction, has neither claimed nor denied responsibility for the kidnappings. Dudin was the second Palestinian killed since these raids began. Troops also critically wounded another Palestinian on the outskirts of Ramallah, Israeli and Palestinian medical officials said. The man, 24, was admitted to an Israeli hospital.

The Israeli military said it had responded with live gunfire when Palestinians threw a hand grenade, causing light injuries to a soldier.

The violence drew criticism from United Nations Middle East envoy Robert Serry, who urged all sides to show restraint and bring about the “immediate release of the kidnapped Israelis”.

U.N. DEMANDS RESTRAINT

“We call for restaint and expect Israel to carry out the related security operations in compliance with international law and respect for the lives, dignity and livelihoods of Palestinians,” Serry said in a written statement to reporters.

“It should thus seek to minimise the impact of security operations on individuals who have committed no offence and investigate allegations of excessive use of force, including the killing of civilians.”

Some 1,150 sites in the West Bank have thus far been searched, the military said, in its mission to weaken Hamas while in pursuit of Gil-Ad Shaer and U.S.-Israeli national Naftali Fraenkel, both aged 16, and Eyal Yifrah, 19.

Israel has also struck out at welfare organisations it accuses of aiding Hamas, which opposes Israel’s existence. Soldiers raided 30 such institutions on Thursday.

Reuters television footage showed soldiers loading files and computers from an office called “Islamic Charitable Society” in Hebron, onto a truck.

Israel also said it was shutting down activities of the British-based Islamic Relief Worldwide (IRW).

In the Gaza Strip, Israeli aircraft bombed three militant targets after rockets were fired at Israel. Five Palestinians living in homes near one of the sites that was bombed were wounded in the air strikes, Palestinian medical officials said.

Palestinian President Mahmoud Abbas has condemned the kidnappings but asserted that the extent of Israel’s raids amounted to collective punishment and urged they be condemned.

Hamas spokesman Sami Abu Zuhri said in Gaza on Thursday that “regardless of who was responsible (for the teenagers’ disappearance)...we stress on the right of our people to react to the agonies of our prisoners in the occupation jails”.