A federal judge on Wednesday blocked President Donald Trump's deployment of National Guard troops in Los Angeles and ordered the troops be returned to the state governor's control.

In June, Trump sent thousands of National Guard troops to the California city in the wake of protests over his administration ramping up immigration raids in Los Angeles.

US District Judge Charles Breyer said the Trump administration had not proven that that the city's protests against immigration justified taking federal control of the state's National Guard.

The Trump administration still has control over 300 troops in Los Angeles six months after they were federalised, Judge Breyer said.

Breyer also denied the Trump administration's argument that the courts should not weigh in on a president taking control of state National Guard troops during an emergency.

"The Founders designed our government to be a system of checks and balances," Judge Breyer wrote in his ruling. "Defendants, however, make clear that the only check they want is a blank one."

Judge Breyer said his order would not go into effect until 15 December, giving the Trump administration time to make its expected appeal to a higher court.

This year, Trump has sent National Guard troops to several cities, including Portland, Oregon, and Washington DC, where the deployments have also been contested in courts and. in some cases, blocked by judges.