Former receptionist Leona is the protege of American Idol judge Simon Cowell, who has taken charge of her career since she won British talent show, the X Factor in 2006, where he is also a judge.

The UK's Press Association reported him as saying: "What Leona has achieved is simply incredible. This is the hardest market to crack and for her debut album to go in at number one is unbelievable."

Leona will also join her mentor on American Idol later this month as she performs live in front of her biggest audience to date.

Her album Spirit has sold 204,841 copies this week in the U.S., while her nearest rival in the Billboard Top 200, the album Troubadour by George Strait, has sold 59,000 copies, according to PA, who spoke to her spokesman.

Leona was signed to SyCo Music, Cowell's division of Sony BMG, after winning the X Factor.

She is signed jointly in America to music mogul Clive Davis's label J Records. Davis, who discovered Whitney Houston, gave Leona his seal of approval, saying: "Leona Lewis will not be an overnight sensation. She is the real deal and this is just the beginning of a long and illustrious career."

Spirit was the fastest selling debut album of all time in the UK and sold more than two million copies within weeks, PA reported.

Her single Bleeding Love has been at hit in 10 countries and was the biggest-selling single of 2007 in the UK, staying at the top spot for seven weeks and selling more than one million copies.