LONDON — A judge ruled on Wednesday that Navinder Singh Sarao can be sent to the United States to face criminal charges accusing him of playing a role in the May 2010 “flash crash” in the United States stock market.

Mr. Sarao will not be sent back to the United States immediately. The judge’s decision will be forwarded to the secretary of state of Britain, who will have two months to review it.

Mr. Sarao’s lawyers said they would appeal the decision after the secretary of state’s review. He remains free on bail during the review.

Mr. Sarao, 36, was arrested in April of last year and has fought extradition to the United States since his arrest.