NEW YORK (AFP) - An incident this week in which former pop star Cat Stevens was deported from the United States to London as a "no-fly" terrorist risk was caused by a spelling error. Stevens, 57, gave up his successful pop career in the late 1970s, taking the name Yusuf Islam and converting to Islam. He had been travelling from London to Washington on Tuesday when his flight was diverted to Bangor, Maine, where he was detained on "national security grounds" and summarily put on a plane to London, according to US security officials. Asa Hutchinson, the US Department of Homeland Security's under secretary for border and transportation security, refused to specify the allegations against Islam. Time magazine, in its on-line edition, quoted aviation sources with access to the "no-fly" list as saying there is no entry on the list under the name "Yusuf Islam," but that there is a "Youssouf Islam" on the list. They said the incorrect name was added to the list this summer.