GENEVA (Reuters) - A Geneva court found a British lawyer guilty of defamation and attempted extortion for writing letters to Western intelligence services accusing his former client, a Russian-led oil trader, of financing terrorism.

An indictment presented to the court by a Geneva state prosecutor said that Matthew Parish, a 44-year-old Cambridge graduate, wrote in a letter to MI5 on April 27, 2018, that Integral Petroleum had close links to terrorist groups such as the Taliban and Islamic State.

Parish also accused the firm of using front companies to carry out what he called “the greatest fraud in recent history”. The indictment said a dispute had arisen between the parties in 2017/2018 over legal bills that Parish said Integral owed him. Parish denied this, saying they fell out over employment terms.

In May 2018, he sent similar letters to U.S. and EU authorities, according to the indictment.

Late on Thursday, a spokesman for the Geneva prosecutor’s office said: “Mr. Parish is found guilty of defamation, calumny, a coercion attempt and of failing to conform with an authority’s decision.”

He said Parish was ordered to pay a fine of 5000 CHF ($5,121) and the full costs of the proceedings and given a suspended sentence of one year in prison.

He was also instructed by the court to see a psychiatrist.

Reuters could not determine how the court reached its verdict. Geneva court rulings are only made public if an appeal is lodged and then only several weeks after the judgment.

David Bitton, lawyer for Integral and a plaintiff in the case, confirmed the verdict by telephone on Thursday. He did not respond to later requests for further comment.

Britain’s interior ministry, which oversees the MI5 domestic intelligence agency, declined to comment. The foreign ministry said it was providing consular assistance to a British man in Switzerland, but gave no other details.

The EU commission did not provide any immediate comment. A spokeswoman for the U.S. Department of Justice declined to comment. The CIA and office of Director of National Intelligence did not respond to a request for comment.

Parish said he would appeal the verdict.

“How can you be found guilty of libel for informing enforcement bodies of crimes, without anyone completing an investigation as to whether those crimes have been committed?” Parish said.

Reuters was unable to confirm whether an investigation had been carried out or was under way.

Bitton, the plaintiff and lawyer for Integral, said in court on Wednesday that Parish’s actions warranted an “especially harsh” verdict.

Bitton told the court that Parish knew the allegations against Integral were false and that he made them in order to pressure the company to pay around 800,000 CHF ($781,000) in fees sought by Parish.

Several other parties, including another Swiss-based oil firm Petroforce Trading and Shipping and Integral’s Russian CEO Murat Seitnepesov, also joined as plaintiffs in the case.

“Matthew Parish gravely damaged (Petroforce’s) honor and it was essential for the firm that the defamatory nature of Mr. Parish’s remarks be formally established,” Marc Hassberger, one of Petroforce’s lawyers, said on Saturday.

“This judgment fully satisfies my client.”

Petroforce and Seitnepesov joined the case because they were also named in the letters Parish sent to intelligence authorities in 2018, according to the indictment.

Integral Petroleum focuses on trading and logistics in the Caspian Sea, the Caucasus, Central Asia and Central America, according to its website. It is one of many commodity trading firms based in the Swiss city.