LONDON - Red Bull have identified a tram as the likely culprit for Mark Webber's retirement in last weekend's Singapore Grand Prix.

The Australian, who has been dogged by bad luck in a 118-race Formula One career, was on course for a podium finish in the first night-time grand prix when his car's gearbox tried to select two gears at once and broke on lap 30.

Team boss Christian Horner told Britain's Autosport magazine on Thursday that it appeared a sudden electrical surge at turn 13 was responsible.

"A tram line runs beneath the track at that corner and it seems as if static from a passing tram at the very moment Mark was in the corner passed through the ground," he said.

Webber was running behind Renault's eventual race winner Fernando Alonso and might have finished second after pitting before the safety car was deployed for the first time.