The mayor of Portland in Oregon has renewed his call for federal troops to leave the US city, accusing them of abusive tactics against protesters.

"They are sharply escalating the situation," Mayor Ted Wheeler told CNN on Sunday.

There have been nightly protests against police brutality in the city since the killing of African American George Floyd in Minneapolis in May.

The federal government has said it is trying to restore order in Portland.

Speaking to CNN on Sunday, Mayor Wheeler said there were "dozens if not hundreds of federal troops" in the city, adding: "Their presence here is actually leading to more violence and more vandalism.

"They're not wanted here. We haven't asked them here. In fact, we want them to leave," he said.

His comments echoed those of Oregon Governor Kate Brown, who described the presence of federal troops in the city as "purely political theatre" from the Donald Trump administration.

Ms Brown told MSNBC that she had asked the federal government on Tuesday to remove the troops, saying: "You are escalating an already challenging situation."

Their comments came after Oregon's attorney general filed a lawsuit against the federal government, accusing it of unlawfully detaining protesters.