US President Donald Trump may hire his son-in-law Jared Kushner to be one of his most influential White House counselors, the US Justice Department said, noting anti-nepotism laws do not apply to the president.

The law "does not bar this appointment because the president's special hiring authority... exempts positions in the White House Office," the Justice Department said in a legal memorandum.

Trump earlier this month named the 36-year-old husband of his daughter Ivanka to be senior advisor to the president.

"Kushner will work closely with chief of staff Reince Priebus and chief strategist Stephen Bannon to execute president-elect Trump's agenda," Trump's team said in announcing the position.

During the campaign Kushner was a major presence on Trump's team, concentrating especially on digital strategy.

Kushner is the scion of an orthodox Jewish family and considered an influential adviser to Trump on Middle East issues. Kushner's father Charles, like Trump, is a major player in the New York real estate scene.

Kushner has chosen to forego his salary while serving in the administration, the statement said.

- dpa