(Adds Ecclestone threat to set up rival series, earlier offer)
By Jörn Poltz
MUNICH, Germany May 13 (Reuters) - A jailed former German banker told a court on Tuesday that Formula One boss Bernie Ecclestone had bribed him when they worked together in the motor sport, supporting the prosecution case in the Briton's trial.
Ecclestone is accused of bribing Gerhard Gribkowsky by channelling $44 million to him in return for smoothing the sale of a stake in Formula One held by bank BayernLB to the private equity firm CVC eight years ago.
The 83-year-old, who denies wrongdoing, could face up to 10 years in prison if found guilty and a conviction would end his long grip on a business he helped to create.
"The offer clearly came from him," Gribkowsky told the court in Munich as Ecclestone followed proceedings with the help of an interpreter. "I accepted the offer."
Gribkowsky, former chief risk officer with BayernLB, said he was culpable for allowing himself to be corrupted.
"I had a carrot dangled in front of me. I grabbed the carrot," he added.
Gribkowsky, who started giving evidence on Friday, has struggled to explain exactly what Ecclestone had demanded in return for payments.
The German told the court that Ecclestone had threatened to leave Formula One and set up a rival motor racing series unless the business was sold to an investor who was to his liking.
He also said Ecclestone had earlier tempted him with the offer of an $80 million payment.
"I would describe that as an attempt at seduction," Gribkowsky said, adding he did not take the offer seriously.
The relationship between Gribkowsky and Ecclestone is the central issue in a case that threatens to cost the Formula One boss his reputation as well as his job.
Prosecutors allege Ecclestone favoured CVC as the new owner because it was committed to keeping him on as chief executive of a business he had built into a global money spinner over the previous three decades.
Ecclestone admits making multi-million dollar payments to Gribkowsky, but says this was to silence the German who he said was threatening to make false claims about his tax status that could have jeopardised his fortune.
The German said he had spread rumours about Ecclestone's tax status during a power struggle over the running of the business, but denied blackmailing him.
"We didn't have anything concrete. It was mainly nuisance value," he said, adding he had told the British tax authorities the same thing when they asked him about Ecclestone's tax affairs.
Gribkowsky had become involved in Formula One after BayernLB acquired a 47 percent stake in the business following the collapse of the Kirch media group in 2002.
The Munich court jailed him for 8-1/2 years in 2012 for corruption over the payments from Ecclestone.
Ecclestone's lawyer Sven Thomas is expected to have the chance to cross examine Gribkowsky when the case resumes on Wednesday. (Writing by Keith Weir in London; Editing by Stephen Brown, David Holmes and Pravin Char)