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US Interior Secretary Ryan Zinke is leaving his post at the end of the year, President Donald Trump says, in the latest high profile departure from his administration.

In a tweet, President Trump thanked Mr Zinke for his service, saying he had "achieved much during his tenure".

He said he would appoint a new interior secretary next week.

Mr Zinke, an ex-Navy Seal and a former Montana congressman, has been embroiled in allegations of ethics violations.

They include a land deal in Montana involving Mr Zinke and the chairman of oilfield services Halliburton, Politico reported.

The interior department oversees federal land, including national parks such as Yosemite and Yellowstone.

Mr Zinke has faced scrutiny over expensive trips in US Park Police helicopters and on private jets.

Costly alterations at his department also came in for criticism, including reports that three sets of double doors in his office were being upgraded at a cost of nearly $139,000 (£110,000). He later said he had negotiated the price down to $75,000.

The New York Times has also published a guide to the investigations into Mr Zinke.

According to the newspaper, he is facing scrutiny for blocking a Native American casino expansion after meetings with lobbyists opposing the plan, and for possible breaches of the Hatch Act - which stops federal employees from influencing elections by using their office.

What's the reaction been?

Mr Zinke has promoted oil drilling and coal mining, and worked to roll back environmental protections brought in under President Obama.

Chuck Schumer, the Senate's most senior Democrat, was blunt in his condemnation.

"The swamp cabinet will be a little less foul without him," he tweeted.

Advocacy groups have accused Mr Zinke of being in hock to corporate polluters, and many welcomed his departure.

Jamie Williams, president of conservation group the Wilderness Society, said he feared what he called the "drill everywhere" policy would continue.

He said: "Unfortunately, even with Secretary Zinke out, the interior department remains disturbingly biased in favour of special interests over the health of American communities and the public lands that they love."

It is not clear if Mr Zinke resigned, or was fired.

News of Mr Zinke's departure comes just a week after the announcement that Mr Trump's chief of staff, Gen John Kelly, is to leave the White House.

On Friday, Mr Trump named his successor, on an acting basis, as Mick Mulvaney, who is currently director of the office of management and budget.

However, video has emerged of Mr Mulvaney calling Mr Trump "a terrible human being" during the 2016 presidential campaign.