The US Supreme Court has struck down affirmative action in college admissions, forcing institutions of higher education to look for new ways to achieve diverse student bodies.

The court’s conservative majority overturned admissions plans at Harvard and the University of North Carolina (UNC), the nation’s oldest private and public colleges, respectively.

Chief Justice John Roberts said that for too long universities have “concluded, wrongly, that the touchstone of an individual’s identity is not challenges bested, skills built, or lessons learned but the colour of their skin”.

He added: “Our constitutional history does not tolerate that choice”.

Justice Sonia Sotomayor wrote in dissent that the decision “rolls back decades of precedent and momentous progress”.

Echoing her dissent, US President Joe Biden said he “strongly, strongly” disagrees with the court’s ruling. He urged colleges not to let the ruling “be the last word”.

“They should not abandon their commitment to ensure student bodies of diverse backgrounds and experience that reflect all of America,” Mr Biden said from the White House.

He said colleges should evaluate “adversity overcome” by candidates.

In a separate dissent, Justice Ketanji Brown Jackson — the court’s first black female justice — called the decision “truly a tragedy for us all”.

Justice Jackson, who sat out the Harvard case because she had been a member of an advisory governing board, wrote: “With let-them-eat-cake obliviousness, today, the majority pulls the ripcord and announces ‘colourblindness for all’ by legal fiat. But deeming race irrelevant in law does not make it so in life.”

The vote was 6-3 in the North Carolina case and 6-2 in the Harvard case. Justice Elena Kagan was the other dissenter.

Two former presidents offered starkly different takes on the high court ruling.

Former president Donald Trump wrote on his social media network that the decision marked “a great day for America. People with extraordinary ability and everything else necessary for success, including future greatness for our Country, are finally being rewarded”.

While former president Barack Obama said in a statement that affirmative action “allowed generations of students like Michelle and me to prove we belonged. Now it’s up to all of us to give young people the opportunities they deserve — and help students everywhere benefit from new perspectives”.

The Supreme Court had twice upheld race-conscious college admissions programmes in the past 20 years, including as recently as 2016.

But that was before the three appointees of former president Donald Trump joined the court.

At arguments in late October, all six conservative justices expressed doubts about the practice, which had been upheld under Supreme Court decisions reaching back to 1978.

Lower courts also had upheld the programmes at both UNC and Harvard, rejecting claims that the schools discriminated against white and Asian-American applicants.