Palestinian medics say two teenage boys have been killed by an Israeli airstrike in the southern Gaza Strip.

Israeli officials Tuesday confirmed the raid, saying it was targeted at a group of militants who had fired mortar shells at Israeli troops.

Israel has tightened security and closed border crossings in Gaza since the militant group Hamas took control of the impoverished territory last year. It has further heightened the blockade in the past month following a series of rocket attacks.

Palestinian Prime Minister Salam Fayyad warned Tuesday that he would not be able to pay December salaries for more than 70,000 Gaza employees until Israel renews cash transfers.

In the West Bank today, Israeli security forces say several Palestinians and Israelis were injured during clashes over a disputed house in the West Bank town of Hebron.

Officials say the violence started Monday night following rumors that security forces were set to remove Jewish settlers defying a Supreme Court order to leave the house they are occupying.

Hundreds of activists gathered to keep security forces from evacuating the house. Clashes then broke out between the protesters and Palestinian residents, with both sides accusing the other of throwing stones.

In several other West Bank locations Tuesday, settlers slashed tires and vandalized a mosque with anti-Islamic graffiti in an apparent response to the Hebron incident.

Israeli Foreign Minister Tzipi Livni, in Brussels to boost EU ties, heard criticism from EU lawmakers about the recent problems in Gaza and the West Bank. Livni told them the international community should continue to support a U.S.-backed peace deal.

She also warned that intervention by outside parties could lead to failure.

Both Israel and the Palestinians acknowledge that a peace initiative launched last year in the U.S. city of Annapolis will not be concluded by the end of the year.

Some information for this report was provided by AFP, AP.