BERLIN (AFP) - Formula One magnate Bernie Ecclestone admits finding the opening day of his German trial stressful as he faced bribery charges which threaten to land the British billionaire in jail.

"It was an exhausting first day. The judge, the prosecutors and my lawyers all speak German, I don't," Mr Ecclestone told German daily Bild from his London office after his first court date in Munich on Thursday.

"Although I had an interpreter translating every word simultaneously, it was still stressful to follow everything as it was being said."

Mr Ecclestone flew back to Britain after hearing five hours of opening arguments with the prosecution's indictment covering 24 pages, while the defence's statement was 91 pages long.

But despite the marathon hearing, the octogenarian still managed to banter with judge Peter Noll.

"Why not?", Ecclestone told Bild. "The court and the prosecutors are all nice people just trying to do their jobs."

The Briton's next court date is scheduled for May 2.

The 83-year-old is accused of paying German banker Gerhard Gribkowsky US$44 million (S$55.2 million) to ensure his continued grip on the motor sports empire he had built up over four decades.

The cash changed hands eight years ago when a German corporate bankruptcy had left several banks in charge of major stakes of the Formula One enterprise.

Mr Gribkowsky was then risk manager of one of the banks, Germany's BayernLB.

Prosecutors charge that the money was a bribe meant to ensure that BayernLB sold its shares to Ecclestone's preferred bidder, CVC Capital Partners of Britain, now the sport's majority shareholder.

Mr Ecclestone faces a maximum jail term of 10 years if he is found guilty.

The F1 boss does not intend to speak for now in the trial, which is set to run until September, but has said he will reply when Mr Gribkowsky gives evidence against him, which is scheduled for May 9.

The case centres on whether Mr Ecclestone bribed Mr Gribkowsky, who has since been jailed, or - as the defence claims - hush money after a blackmail attempt.

Mr Ecclestone's lawyer has dismissed the allegations as "inaccurate, misleading and unsubstantiated" and said "the alleged bribery did not take place".