Israeli troops clashed with Palestinian stone-throwers at two contested holy sites and in a West Bank village Friday, seriously injuring a Palestinian woman and a 14-year-old boy, officials and witnesses said.

At the Jerusalem shrine, home to the Al-Aqsa Mosque, hundreds of Muslim worshippers emerging from prayers threw stones at policemen and Jews praying below at the Jewish shrine known as the Western Wall, according to Israeli police.

Riot police carrying plexiglass shields rushed in, firing tear gas and stun grenades, and charged the youths throwing stones amid the compound's stone buildings and cypress trees.

It was one of the most violent clashes in several years at the site, known to Jews as the Temple Mount and to Muslims as the Noble Sanctuary.

Friday's events were sparked, in part, by rising anger over Israel's decision to add two West Bank shrines to its list of national heritage sites.

While the decision has no immediate consequences, Palestinians perceive it as another sign that Israel wants to hang on to large parts of the West Bank, one of the territories Palestinians want for their state.

In Gaza, some 4,000 supporters of the Islamic militant group Hamas called for a new uprising in the West Bank, urging Hamas' rival, Palestinian President Mahmoud Abbas, to "unleash the resistance" over the shrines.

Friday's violence erupted ahead of a new mission by U.S. Mideast envoy George Mitchell who was to arrive in the region over the weekend to help launch indirect Israeli-Palestinian negotiations.

The Palestinians have been reluctant, arguing that talks are futile as long as Israel keeps expanding Jewish settlements on land they want for a state. However, Arab nations earlier this week gave Abbas the political backing to conduct such talks for four months, with Mitchell shuttling between the sides.

The United States also offered written assurances to Abbas, Palestinian negotiator Saeb Erekat said Friday. In the document, the U.S. promises to assign blame if the talks fail.

"If one side, in our judgment, is not living up to our expectations, we will make our concerns clear and we will act accordingly to overcome that obstacle," said the document.

Israeli Prime Minister Benjamin Netanyahu has called for direct talks, but the Palestinians fear he is not serious about a deal and instead wants open-ended negotiations as a way of deflecting international pressure.

The clashes in Jerusalem and the West Bank erupted after Friday prayers.

At the walled compound in Jerusalem, 13 Palestinians and 18 police officers were hurt, according to police and medics. Among them was a Palestinian woman who was hit in the head by a rubber bullet and was hospitalized in serious condition, an Israeli hospital official said. Police denied using rubber bullets.

In the West Bank village of Nabi Saleh, a 14-year-old boy was critically wounded by a rubber bullet, medics said.

A witness, Israeli activist Jonathan Pollack, said soldiers fired from a rooftop in the village at stone throwers and that the boy was hit from a range of about 20 meters.

The Israeli military said soldiers fired rubber bullets in the village to disperse a violent riot.

Skirmishes also broke at a contested holy site in the West Bank city of Hebron, but no serious injuries were reported.

The Hebron site is one of the two included on the Israeli national heritage list.