Becker threatened with three years in jail for tax evasion

German state prosecutors called yesterday for the former tennis star Boris Becker to serve a three-and-a-half-year prison term for failing to pay €1.7m (£1.1m) of tax in Germany in the early 1990s.

At the opening of his trial in Munich on tax evasion charges, the state prosecutor Matthias Musiol said Mr Becker was clearly guilty because between 1991 and 1993 he had deceived the authorities by secretly living in a Munich apartment while claiming to be a resident of Monaco.

The three times Wimbledon champion admitted making "mistakes" over tax payments, and his lawyers disclosed that he had already paid €3m (£2m) owing in tax to the Munich fiscal authorities.

But the prosecution remained adamant that Mr Becker should go to prison: "The accused has done nothing to assist the investigation. He may have confessed and paid off his tax debts but this only happened at the last minute when it became clear that he was unlikely to be acquitted," Mr Musiol told the court after demanding that Mr Becker be jailed.

Defence lawyers are calling for a two-year suspended sentence, but legal observers said that if the judges upheld the prosecution's demands, Mr Becker would certainly go to jail because under German law the courts can not commute sentences of three years and above to suspended prison terms.

The court is due to pass sentence today.

At the start of the proceedings, Mr Becker told the court: "I admit that I made a mistake 10 years ago and I know that I will have to pay the consequences for that."

Claiming his rooftop apartment in the expensive Munich suburb of Bogenhausen was not his permanent place of residence, he insisted: "The accommodation provided at the Olympic Games is more comfortable. My apartment did not even have a fridge."

The 34-year-old also claimed to have only a scant knowledge of German tax legislation. "I still don't fully understand the ins and outs of the complicated tax system," he said, adding that he had been only interested in tennis and "now and again girls" during his career which began at the age of 16 when he officially moved to Monaco.

Mr Becker nevertheless blamed Munich tax officials for prematurely ending his tennis career in 1999 by making a series of raids on his own and his parents' premises in which crateloads of documents were confiscated. More than 50 files concerning the Becker case were on show in the court. "The strain was just too much," Mr Becker said.

The trial is the latest in a series of personal disasters to befall Mr Becker since he quit professional tennis.

Last year he was forced to pay an estimated €1.5m to a young Russian woman after he acknowledged fathering her child. The woman claimed she had sex with Mr Becker in the cloakroom of a London restaurant.

In January 1991, Mr Becker was divorced from his wife Barbara Feltus after an acrimonious break-up that ended with her taking their two sons to live in Miami. The settlement is reported to have cost him €10m. Two of Mr Becker's businesses have gone bankrupt over the past two years, and his villa in Majorca has become another focus of controversy. The building is still not complete after several years' construction.