Washington, Nov 21, 2017 (AFP) -The United States said Tuesday that President Robert Mugabe's resignation offers Zimbabwe's people a "historic opportunity" for change and could help end its isolation on the world stage.

Washington has been reluctant to call the military takeover that acted as a catalyst for the longtime ruler's resignation a coup, and seized on his departure to try to turn a page.

"With the resignation of Robert Mugabe, today marks a historic moment for Zimbabwe," US Secretary of State Rex Tillerson said, as jubilant crowds took to the streets of Harare.

"We congratulate all Zimbabweans who raised their voices and stated peacefully and clearly that the time for change was overdue," he said.

"Zimbabwe has an extraordinary opportunity to set itself on a new path."

Earlier, Parliament Speaker Jacob Mudenda had read out a resignation letter from the outgoing president, putting an en to his 37-year autocratic reign.

There was no love lost between the US and Mugabe's government, and Zimbabwe remains under tough sanctions, but Washington did not rush to welcome last week's military takeover.

But, as the veteran leader's own party moved to impeach him, Tillerson felt able to express hope that the action would not play out like a typical coup and may allow room for reform.

"The United States strongly supports a peaceful, democratic and prosperous Zimbabwe," he said.

"As events unfold, we continue to call on all parties to exercise restraint and respect constitutional and civilian order," he continued.

"We urge Zimbabwe's leaders to implement much-needed political and economic reforms for a more stable and promising future for the Zimbabwean people.

"Whatever short-term arrangements the government may establish, the path forward must lead to free and fair elections. The people of Zimbabwe must choose their own leaders."