The US Supreme Court has lifted a federal judge's ban on Los Angeles immigration officers from conducting "reasonable suspicion" searches.

Monday's court ruling marks a victory for President Donald Trump's administration, which has pushed to deport illegal immigrants.

The conservative-majority Supreme Court ruled 6-3 to allow immigration officers to conduct background checks based on race, language or occupation.

Moderate judges said the decision threatened constitutional freedoms.

Conservative Justice Brett Kavanaugh wrote in the ruling that the lower court was overreaching in limiting how Immigration and Customs Enforcement officers conduct their searches of suspected illegal immigrants.

"To be clear, racial identity alone is not a reason for suspicion," said the judge. "However, there may be substantial doubt along with other factors," he said in the ruling.

The three moderate justices, represented by Justice Sonia Sotomayor, issued a strong dissent.