The United States will demand that Israel refrain from construction in both the West Bank and East Jerusalem as part of a 90-day settlement freeze Secretary Hillary Clinton has requested in exchange for a package of incentives, a U.S. official told Haaretz on Thursday.

Prime Minister Benjamin Netanyahu is scrambling to gather cabinet support for the settlement freeze. The ultra-Orthodox party Shas currently holds the balance of votes on the matter.

Although the prime minister is unlikely to win their support, Shas ministers have said they will abstain in the vote, provided the final agreement specifically excludes East Jerusalem from the freeze.

Netanyahu met with Shas Chairman Eli Yishai and Minister Ariel Attias on Wednesday in a bid to convince them not to vote down the settlement freeze when the motion is brought to cabinet.

But the U.S. official told Haaretz that "If the moratorium deal goes through, we will continue to press for quiet throughout East Jerusalem during the 90 days, regardless of what Bibi [Netanyahu] is telling Shas now."

The official added that President Barack Obama had committed in an oral message to Palestinian President Mahmoud Abbas last April that the U.S. expects both sides to refrain from "actions that would seriously undermine trust," including in East Jerusalem, and would respond with "steps, actions, or adjustments in policy" to any such provocative actions as long as negotiations are underway.

The U.S. administration has defined "actions that would seriously undermine trust" as including major housing announcements, demolitions, or evictions in East Jerusalem.

"This policy will continue if the negotiations resume under a 90-day moratorium and the Israelis know it", said the US official. "So whatever Bibi is telling Shas to reassure them about U.S. policy on East Jerusalem is not true."

Meanwhile, an official close to the Shas party said Thursday that Defense Minister Ehud Barak has promised to authorize construction of hundreds of apartments in the West Bank immediately after the U.S.-encouraged moratorium expires.

The Shas official said that party had received assurances that should it abstain from the cabinet vote, construction would take place in specifically ultra-Orthodox communities and other projects would be built in a settlement just outside Jerusalem.

The official spoke on condition of anonymity because the deal has not been officially announced. The Defense Ministry couldn't immediately be reached for comment.

Netanyahu said late Wednesday that he was close to reaching understandings on the agreement, and a U.S. official said that Washington was drafting a letter detailing understandings on the proposed 90-day moratorium.

Netanyahu, who has said he would push hard to clinch a deal, also wants the U.S. letter to spell out that the proposed moratorium would be the last. A vote could come as early as Thursday, though officials said nothing had been scheduled by early morning.

To entice the Israelis to sign on to the deal, the U.S. has proposed a package of incentives including a gift of 20 next-generation stealth fighter planes and U.S. pledges to veto anti-Israel resolutions at the United Nations, Israeli officials have said.

During the 90-day freeze period, the U.S. hopes Israel and the Palestinians would make significant progress toward working out a deal on their future borders. With borders determined, Israel could then resume building on any territories it would expect to keep under a final peace deal.