Two US attorney generals have announced that they will sue President Donald Trump on Monday, alleging that he has violated anti-corruption clauses in the Constitution by accepting millions in payments and benefits from foreign governments.

The lawsuit, the first of its kind brought by government entities, centres on the fact that Trump chose to retain ownership of his company when he became President, reports The Washington Post. 

Trump said in January that he was shifting his business assets into a trust managed by his sons to eliminate potential conflicts of interests.

But District of Columbia (D.C.) Attorney General Karl A. Racine and Maryland Attorney General Brian E. Frosh (D) said Trump has broken many promises to keep separate his public duties and private business interests. 

According to Racine and Frosh, the lawsuit could open a new front for Trump as he navigates investigations by special counsel Robert S. Mueller and congressional committees of possible collusion between his associates and the Russian government during the 2016 presidential campaign.

If a federal judge allows the case to proceed, one of the first steps will be to demand through the discovery process copies of Trump's personal tax returns to gauge the extent of his foreign business dealings.

"This case is, at its core, about the right of Marylanders, residents of the District of Columbia and all Americans to have honest government," Frosh told The Washington Post on Sunday night, referring to part of the Constitution known as the emoluments clause, which prohibits US officials from taking gifts or other benefits from foreign governments. 

"The emoluments clauses command that the President put the country first and not his own personal interest first." 

Racine said he felt obligated to sue Trump in part because the Republican-controlled Congress has not taken the President's apparent conflicts seriously.

"We're getting in here to be the check and balance that it appears Congress is unwilling to be," he told the daily.

The suit will seek an injunction to force Trump to stop violating the Constitution but will leave it up to the court to decide how that should be accomplished.