President-elect Donald Trump has said he had formally handed over "complete" control of his business empire to his two sons and they will not discuss its operations with him, in a move to avoid conflicts of interest once he assumes office.

"My two sons – Donald Jr. and Eric – are going to be running the company. They are going to be running it in a very professional manner. They're not going to discuss with me its operations," Trump, surrounded by his sons, daughter and son- in-law, said in his first formal press conference in six months.

"I have signed documents turning over complete and total control to my sons," he said, before handing the stage to his lawyer Sheri Dillon.

Dillon said Trump's assets will be transferred to a trust under the control of his sons before his inauguration and he will step down from his role as an executive at his company.

His commercial real estate assets and licensing businesses will be placed into the trust, along with his cash holdings.

She said Trump's business empire will undertake no foreign deals while he is US president, but underlined that he "should not be expected to destroy the company he built".

"The trust agreement as directed by President Trump imposes severe restrictions on new deals. No new foreign deals will be made whatsoever during the duration of Trump's presidency," she said, adding that the group has terminated more than 30 pending deals in recent weeks.

Trump said his organisation's business will continue to pursue deals in the US.

He disclosed that over the weekend he was offered "USD two billion" to do a "number of deals" in Dubai "from an amazing man, a friend of mine" but he turned it down even though he was not required to do so.

"I turned it down. I didn't have to turn it down. I could actually run my business and government at the same time. I don't like the way it looks. But I don't want to do that," he said.

The press conference comes nine days before Trump is set to be sworn in as the 45th president of the US and nearly a month after Trump cancelled his last scheduled news conference.

With Trump's swearing-in just days away, key members appointed by him to his cabinet are facing nomination hearings.

There is intense scrutiny about how Trump will distance himself from his global business empire and avoid conflict of interests as leader of the most powerful country in the world.