South Korea could block broadcasts of World Cup matches to football-mad Pyongyang, venting anger over the loss of a warship before North Korea make their first appearance in the tournament since their giant-slaying performance of 1966.

Seoul has few practical responses to the loss of a corvette, which it suspects North Korea torpedoed in late March, killing 46 sailors. Pulling the plug on coverage of next month's World Cup finals could touch a nerve.

North Korea, perhaps the competition's most celebrated underdogs, knocked out Italy in 1966 before surrendering a 3-0 lead against Eusebio's Portugal to lose in the quarter-finals. Football stokes high emotions in the North and the only riot filmed there followed a match against Iran in 2005, when fans hurled seats and bottles on to the pitch.