Donald Trump sold all his shares in companies five months ago, according to his spokesman, creating funds during the campaign trail and helping to divert from a potential conflict of interest.

His stock portfolio was worth about $40 million as of December 2015, according to a May disclosure filing and as reported by the Washington Post.

He invested in banks, oil companies and other stocks that have business pending with the US government.

Mr Trump gave his campaign about $47 million of his own money, with the first donation of $2 million dated 22 June.

Total money from his own pocket came to $66 million - falling short of the pledged $100 million - and much of the campaign was funded by donors.

Trump’s campaign team has not provided any records of stock transactions since the May document, therefore there is no official way to check the statement that he sold his portfolio.

Any company that the president-elect had a stake in and which rose in value due to his decisions in office would create a conflict of interest.

Mr Trump’s communications director Jason Miller did not reveal why Mr Trump had sold the shares or the value of them at sale. Mr Trump's next required personal financial disclosure form is not due until May 2018.

The businessman, who owns a real estate empire, has faced increasing calls to divest from all of his commercial enterprises as he could risk breaching the US constitution as soon as he enters the Oval Office. His latest venture, the new hotel in Washington DC opposite the White House, has already been used to host foreign diplomats, giving them a tour of the expensive suites.

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Selling all his shares has been described as a step in the right direction for the incoming president.

The 2012 STOCK Act requires government officials to publicly disclose any stock transactions worth at least $1,000 within 45 days.

Mr Trump used to be a shareholder in Boeing, owning between as much as $100,000 of the stock in the May filing. He then tweeted on Tuesday that the airplane manufacturer’s costs were “out of control” and its government contract should be canceled. The single tweet wiped as much as $1 billion from the stock. He has already divested from Boeing, said his spokesman.

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He has also reportedly divested from his shares in Energy Transfer Partners, the company that is building the controversial oil and gas pipeline that cuts through the Missouri River.

Norman Eisen, the former ethics counsel for president Barack Obama, told the Post he wanted to know what Mr Trump has done with the money, and whether he had thereby created new conflicts of interest.

The president-elect recently promised to divest from his real estate businesses because it is "visually important" and will house the assets in a blind trust - further details are expected on 15 December.