A Swiss banker who publicised private client data on WikiLeaks was found guilty today of breaching strict banking secrecy and threatening former colleagues, but was given only a suspended fine.

The judge acquitted Rudolf Elmer on charges he sought $50,000 (£31,250) for returning client data to former employer Julius Baer and that he made a bomb threat to the bank's headquarters.

Elmer, who helped bring WikiLeaks to prominence three years ago when he used it to publish secret client details and who handed over new data to the website on Monday, had admitted sending Julius Baer data to tax authorities.

But he had denied blackmail and a bomb threat against Baer, and said he had never taken payments in return for secret data.

The court sentenced him to a fine of 7,200 Swiss francs (£4,700), suspended for two years, without giving reasons; those will come in a written judgment. The prosecution had called for an eight-month jail term and a fine of 2,000 francs.

The defence will decide whether to appeal within 10 days.

Elmer, 55, who ran the Cayman Islands branch of the Swiss bank dedicated to wealthy clients until he was fired in 2002, spent a month in investigative custody in 2005 when the charges were first made against him.

"I am a critic of the system and want to tell society what happens in these murky oases," he told a news conference before the verdict.

Elmer claimed Baer had waged a campaign of "psycho-terror" against him and his family, and had offered him 500,000 francs to keep quiet. He said he had never taken payments in return for secret data.

But he admitted writing anonymous emails in 2005 threatening to send client details to tax authorities and to the media if Baer did not stop unspecified actions.

"The situation was very threatening, he told the court. "We were very scared and I thought the bank was behind it. That is why I sent the emails."

Wearing a black suit and a red shirt, Elmer also admitted charges that he had sent client details to Swiss tax authorities, but he denied making threats against former colleagues.