The Middle East Quartet said Tuesday that they were alarmed by Israel's latest announcements about new settlement plans in the West Bank and East Jerusalem.

The so-called quartet, made up of the United States, Russia, the European Union and the United Nations, released a statement expressing deep concern regarding Israel's recent announcement to build 277 homes in the Ariel settlement in the West Bank, as well as more than 900 housing units in Har Homa in East Jerusalem.

"The Quartet is greatly concerned by Israel's recent announcements to advance planning for new housing units in Ariel and East Jerusalem," the mediating group said in a joint statement.

On Monday, the U.S. said it found reports of fresh Israeli settlement building plans deeply troubling and counterproductive to the U.S. effort to revive Israeli-Palestinian peace negotiations.

The Palestinian leadership also sharply criticized Israel on Monday. Nabil Abu Rdainah, spokesman for Abbas, told Reuters: "This act is condemned and is an Israeli attempt to obstruct and destroy what is left of any effort to revive the peace process.

"Once again, these Israeli settlement measures represent a strong reason calling on us to go to the United Nations and the Security Council to request membership for the State of Palestine and to halt these Israeli measures," he said.