Obama leaves early but Nobel band plays on

The guest of honour was an ocean away, but the show went on.

The royal purple box seat reserved for US president Barack Obama - the 2009 Nobel Peace Prize winner - remained empty last night, as artists worldwide took the stage at the annual concert in honour of the year's laureate.

But breaking Nobel protocol, the American president left the Norwegian capital Oslo early, blaming a busy schedule for cutting the planned three-day visit to just over 24 hours.

Haitian-born musician Wyclef Jean stole the show with Gunpowder, an anti-war anthem performed with Chinese classical pianist Lang Lang, who earlier played George Gershwin's Rhapsody in Blue at the Nobel awards ceremony.

Jean also managed to achieve the seemingly impossible - getting Norway's crown prince and princess to throw their hands in the air for his final song.

Disco sensation Donna Summer, the show closer, also brought the crowd to its feet with a medley of hits from the 1970s and 1980s.

Other artists included Malian blues duo Amadou and Mariam and American country music star Toby Keith.

Keith spoke to journalists alongside Nobel concert hosts - film star and rapper Will Smith and his wife, actress Jada Pinkett Smith.

Smith, whose interview with Obama during the president's stay in Oslo was shown at the concert last night, said he had no reservations about Obama's peace prize despite his status as an early first-term wartime president.

Keith also defended Obama's decision when meeting journalists in Oslo.

Speaking to his feelings about his laureateship, Obama said during his interview with the Smiths that "this is one of those events that happens in your life that I suspect you appreciate more in retrospect".