Donald Trump signaled that his businesses will carry out "no new deals" during his presidency in a series of tweets late Monday, adding that his two adult sons would manage his companies.

Writing on Twitter, Trump -- who has been criticized for the conflict of interest that his vast business empire would pose for a US president -- said: "Even though I am not mandated by law to do so, I will be leaving my busineses (sic) before January 20th so that I can focus full time on the Presidency."

Critics argue that it would be an unprecedented ethical conflict for Trump to maintain interest in properties spanning the globe -- investments that rely partly on goodwill from foreign governments and regulators.

"Two of my children, Don and Eric, plus executives, will manage them. No new deals will be done during my term(s) in office," the president-elect tweeted.

Trump's daughter Ivanka was notably absent from the list. Her husband, Jared Kushner, is a close adviser to her father who is expected to play a role in Trump's presidency.

"I will hold a press conference in the near future to discuss the business, Cabinet picks and all other topics of interest," Trump wrote on Twitter. 

The 70-year-old tycoon, who has multi-billion-dollar global property and luxury branding interests, had previously scheduled a press conference on his global business dealings for December 15, but on Monday he postponed it until January.

Speaking on CNN, his top advisor Kellyanne Conway attributed the delay to "how convoluted and complex many of these business holdings are," adding that Trump still intends to relinquish operational control of his company while serving as president.

"He's just a man who's been incredibly successful and has holdings all across the globe."

US law does not require Trump to give up his business portfolio, although the Constitution states no federal official can receive a gift or "emolument" from a foreign government.

Some previous presidents have placed their investments in a blind trust, but they were not required to do so and since winning the election in early November, Trump has said his lawyers believe it unnecessary.

Even on home soil, his company has been attacked for marketing the new Trump International Hotel in Washington -- just blocks from the White House -- to foreign diplomats.