Masked Palestinians use a back car seat as a shield during a protest to support Palestinian prisoners, outside Ofer, an Israeli military prison near the West Bank city of Ramallah. (Bernat Armangue/AP)

Palestinian protesters clashed with Israeli forces at flashpoints in Jerusalem and across the West Bank on Friday, capping a week of demonstrations in support of four Palestinian prisoners on extended hunger strikes against their incarceration.

Two of the prisoners are being held without trial, and two were rearrested after being released in a prisoner exchange in 2011.

Israeli police briefly entered the compound of the al-Aqsa mosque in Jerusalem, also known as the Temple Mount, and used stun grenades to disperse dozens of protesters who pelted them with stones after Friday prayers, a police spokesman said.

Clashes also erupted after a march by hundreds of Palestinians in the West Bank city of Hebron, where Israeli troops used stun grenades and tear gas to repel stone-throwers in the city’s old quarter, adjacent to several Jewish settlement enclaves, according to reports from the scene.

Hundreds of protesters clashed with troops at a checkpoint near Jenin in the northern West Bank, the army said, and confrontations continued for the second consecutive day near the Ofer prison outside Ramallah.

A military spokeswoman said protesters in several locations hurled stones and molotov cocktails at troops and set up barricades of burning tires. She said Israeli forces responded with nonlethal riot-control weapons.

Palestinian emergency services said dozens of people were treated for tear-gas inhalation and injuries from rubber-coated bullets.

The worsening condition of the prisoners has raised tensions in the West Bank and brought expressions of concern this week from U.N. Secretary General Ban Ki-moon and the European Union. Two of the striking prisoners were hospitalized Thursday, according to a spokeswoman for the Israeli Prisons Service.

“If any of the prisoners die, it will set the occupied territories on fire,” warned Ziad Abu Ein, the deputy minister for detainee affairs in the Palestinian Authority, who joined a protest Thursday near the Ofer prison.

With about 4,600 Palestinians in Israeli jails, the issue of the prisoners touches many Palestinian families directly.

Viewed by Palestinians as heroes of the struggle against Israeli occupation, the prisoners evoke expressions of support across the political spectrum. Thursday’s demonstration was organized by the Fatah party of Palestinian Authority President Mahmoud Abbas, but some participants wore the colors of the Islamist Hamas movement and smaller leftist groups.

As several hundred chanting demonstrators marched Thursday from the town of Beitunia toward the Ofer jail, they were met by a hail of tear gas canisters fired by Israeli border police lined up outside the prison, about 100 yards away. The crowd ran for cover as masked youths, some using slingshots, hurled stones and set up barricades of burning tires, provoking more volleys of tear gas and the firing of rubber-coated bullets.

As the clashes continued into the afternoon, ambulances ferried away casualties. The Palestinian Red Crescent later reported 27 people injured and about 30 others treated for tear gas inhalation Thursday.

Some of the protesters carried posters bearing the image of Samer Issawi, 35, who has been on an intermittent hunger strike for more than 200 days, taking only water and nonfood supplements, according to Palestinian and Israeli human rights groups monitoring his case.

Sentenced in 2002 to 26 years in prison for several shootings and providing weapons for other attacks in the West Bank and Jerusalem, Issawi was released in October 2011 as part of a prisoner exchange that freed Gilad Shalit, an Israeli soldier held captive in the Gaza Strip by Hamas. Issawi, who lives in Jerusalem, was arrested last year for entering the West Bank in violation of the terms of his release. Accused of undisclosed security offenses, he faces possible imprisonment for the remainder of his original term, under amended Israeli military law.

Ayman Sharawna, who has been on an intermittent hunger strike since July, was sentenced to 38 years in 2002 for a bombing in the southern Israeli city of Beersheba that wounded 18 people. Released in the Shalit prisoner swap, he was rearrested last year for alleged security violations not disclosed to his lawyer. He too may face imprisonment for the remainder of his original jail term.

Two other prisoners who have refused food for nearly three months are protesting their incarceration without charges or trial, known as administrative detention. Israeli security officials accuse the two of being activists with the Palestinian militant group Islamic Jihad.

In his statement Tuesday, Ban said he was “deeply concerned over the rapidly deteriorating condition” of the prisoners on hunger strike, adding that those detained without trial should be charged or released. Expressing similar concerns, E.U. foreign policy chief Catherine Ashton called on Israel to restore family visiting rights taken away from the striking prisoners and to “respect international human rights obligations towards all Palestinian detainees.”