U.S. President-elect Donald Trump's son-in-law, Jared Kushner, will become a senior White House adviser working on trade and the Middle East, transition officials said on Monday, in a rare case of a close presidential family member taking a major job.

Kushner, 35, who is married to Trump's daughter Ivanka, is taking the post after receiving legal counsel that doing so would not violate U.S. anti-nepotism law, transition officials said. The position, unlike Cabinet posts, does not require U.S. Senate confirmation, and Kushner will not be paid.

Trump, in a statement on Monday announcing the choice, said Kushner was a "tremendous asset and trusted advisor throughout the campaign and transition."

Kushner, who like Trump is a New York real estate developer, emerged as an important voice early in his father-in-law's presidential campaign and was involved in almost every aspect of it from personnel decisions to strategy and fundraising.

Ivanka Trump, who like her husband has been a close adviser to the president-elect, will not take on a role in her father's White House but will focus on settling her family in Washington.

Kushner is to work closely with incoming White House Chief of Staff Reince Priebus and senior strategist Steve Bannon in advising the new president, and the officials said he would focus at least at first on trade policy and the Middle East.