The death was announced by Hannover president Martin Kind, who said the goalkeeper had been “unstable” after he and his wife lost their two-year-old daughter due to heart problems in 2006.

“I don't know why and how this happened. All I can say for sure is that it had nothing to do with football,” he added.

Robert Enke was named the best goalkeeper of the German Bundesliga last season. The national team’s coach Joachim Löw considered him to be his No. 1, and it was only illness that prevented him from playing in a crucial World Cup 2010 qualifier against Russia in October.

Enke had seven caps for his country and was sure to travel to South Africa next summer.

German football has been shocked by the news. The national squad has cancelled all training sessions and interviews on the day, with the team’s manager Oliver Bierhoff saying: “We are all just speechless.”

Hundreds of fans also gathered to light candles outside the Hannover 96 offices after learning of Enke's death.

Enke started his career in 1995 in Carl Zeiss Jena. He then defended the colors of such teams as Borussia Mönchengladbach, Benfica, Barcelona and Hannover, playing 287 matches in all.