The United States has asked Israeli Prime Minister Benjamin Netanyahu to keep alive the prospect of a Palestinian state as he considers West Bank annexation, a senior official said Thursday.

Netanyahu's government had set July 1 as the date when it could begin formally taking over Palestinian areas seized in 1967 in line with a plan outlined in January by US President Donald Trump.

Trump's plan also lays out the grounds for an independent Palestinian state, although it would be demilitarized and its capital would not be inside the contested holy city of Jerusalem.

David Schenker, the top US diplomat for the Middle East, said that Netanyahu was facing domestic pressure as some of his supporters "want annexation but aren't particularly enamored of the vision for peace that calls for a Palestinian state as well."

"So we're calling on the Israelis not to do anything that would preclude the implementation of the vision," Schenker said at the German Marshall Fund of the United States.

He said he was unsure if Netanyahu would ultimately go ahead with annexation as he assesses the impact it would have.

"It wouldn't surprise me if we didn't see anything, but I think that the prime minister would like to do something," Schenker said.

Trump's administration, whose evangelical base is strongly pro-Israel, has said that Netanyahu has Washington's green light to annex Palestinian land.

But Schenker said Israel was aware of the threat of repercussions from European powers as well as strong objections from friendly Arab states.

The Palestinian Authority has rejected the Trump plan, accusing the administration of bias and of trying to buy off the Palestinians through promises of future investment.