Rhymes, 36, was detained at London City Airport by immigration officers, who said their refusal was based on “unresolved convictions” in the United States, said Stephen Greene of Orange RockCorps.

The performer remained in custody in London while RockCorps took legal steps to try to reverse the decision.

The promoter said Rhymes, whose real name is Trevor George Smith Jr., had been allowed into Britain twice before this year. He was to appear at a concert Friday at London’s mammoth Albert Hall.

U.S. rap star Ludacris has agreed to perform in Rhymes’ place.

On its Web site, RockCorps said even though lawyer Philip Trott presented papers to support the rapper’s case for entry, immigration authorities arranged to fly him back to Amsterdam. The rapper’s lawyers then got an injunction from a High Court judge to prevent him from being sent back.

“He is currently detained, pending a decision on temporary admission by the immigration officer,” the promoter said in a statement.