Republicans in the US Congress announced an investigation into Harvard University on Thursday, accusing it of flouting civil rights law in an escalation of President Donald Trump’s attacks on elite institutions.

The lawmakers wrote to the world-renowned education and research establishment demanding documents on its hiring practices, diversity programmes and last year’s pro-Palestinian campus protests.

The letter – signed by House Oversight Committee chair James Comer and House leadership chair Elise Stefanik – came with Trump seeking unprecedented levels of control over the country’s oldest and wealthiest university.

Comer and Stefanik castigated Harvard president Alan Garber for rejecting demands for supervision by the White House, which has cancelled US$2.2 billion in funding and threatened further reprisals.

“Harvard is apparently so unable or unwilling to prevent unlawful discrimination that the institution, at your direction, is refusing to enter into a reasonable settlement agreement proposed by federal officials intended to put Harvard back in compliance with the law,” they told Garber.

“No matter how entitled your behaviour, no institution is entitled to violate the law.”

Trump – furious at Harvard for rejecting oversight of its admissions, hiring practices and political slant – told reporters the university’s conduct had been “horrific”.