WASHINGTON (Reuters) - The United States on Wednesday voiced concern about a significant acceleration of Israeli settlement activity in Palestinian territories and said a policy of retroactively approving unauthorized settlements allow the Israeli government to expand such activity in a "potentially unlimited way."

"We are deeply concerned by the government’s announcement to advance plans for these settlement units in the West Bank," State Department spokesman John Kirby said at a news briefing.

"We are particularly troubled by the policy of retroactively approving unauthorized settlement units and outposts that are themselves illegal under Israeli law. These policies have effectively given the Israeli government a green light for the pervasive advancement of settlement activity in a new and potentially unlimited way."

(Reporting by Arshad Mohammed; Writing by Mohammad Zargham; Editing by Eric Beech)