WASHINGTON, Aug. 7 (Barron's) - The United States on Wednesday voiced support for ally Britain as police respond to nightly riots that have erupted against Muslim and migrant targets.

State Department spokesman Matthew Miller said that the United States supported freedom of assembly "but that does not in any way justify violence, does not justify rioting."

"UK authorities are well within their rights to use all law enforcement authorities to hold those accountable who engage in violent activities," Miller told reporters.

The far-right violence erupted after three children were murdered in a knife attack at a Taylor Swift-themed dance class in Southport, northwest England.

Online disinformation said the assailant was Muslim or a recent migrant, and far-right social media channels have since advertised the rallies.

Tech billionaire Elon Musk, who was born in South Africa and has US citizenship, has angered the UK government with a series of provocative tweets, including one that said a British "civil war is inevitable."