LONDON (AP) — Self-exiled tycoon Boris Berezovsky lost his multibillion-dollar legal battle against a fellow Russian oligarch on Friday, with a British judge ruling that Roman Abramovich was the more truthful witness in their clash over vast oil wealth.

The case in London's High Court had sparked broad interest because of its focus on the two oligarchs' personal, as well as business, relationship in the chaotic days of post-Soviet Russia. The weeks of testimony included juicy details about both jet-setters' lifestyles — including yachts, vacations and spending on luxury goods.

Berezovsky, a former Kremlin power broker, had alleged that Abramovich, who he called his protege, had betrayed and intimidated him into selling his stakes in the Russian oil company Sibneft significantly beneath their value.

Abramovich had denied the allegations.

On Friday, Judge Elizabeth Gloster ruled the 66-year-old Berezovsky was not as reliable as a witness as the 45-year-old Abramovich, the billionaire owner of the Chelsea soccer club.

"The bottom line of my analysis of Mr Berezovsky's credibility is that he would have said almost anything to support his case ," Gloster said in her judgment.

On the contrary, the judge said she found "Abramovich to be a truthful, and on the whole reliable, witness."

Berezovsky, who appeared Friday in court, alleged blackmail and breach of contract and was seeking more than three billion pounds (US$4.8 billion) in damages.

Abramovich did not attend Friday's proceedings.

The two men were said to have become friends after meeting on a private cruise in the Caribbean, built a business empire together, but parted bitterly when their fortunes were reversed.

Berezovsky, a mathematician-turned-Mercedes dealer, amassed his wealth during Russia's privatization of state assets in the early 1990s. In return for backing former Russian President Boris Yeltsin, he gained powerful political connections and access to valuable assets at very low prices.

Berezovsky says he mentored the younger Abramovich, treated him like a son, and founded Sibneft with him and a third partner. Berezovsky claimed that the friendship faltered when he fell out with Russian leader Vladimir Putin, at which point Abramovich "intimidated" him into selling his Sibneft shares — causing him losses of almost US$6 billion.

Abramovich claims that Berezovsky was not his mentor and never owned the stakes — in fact, he argued that Berezovsky only had a political role in creating Sibneft and never "contributed a single cent" to acquiring or building up the company.

The Chelsea owner said he had already paid more than US$2.5 billion to Berezovsky for his services as his "political godfather" — a protector whose political influence helped him do business in Russia — and reluctantly funded Berezovsky's extravagant lifestyle of yachts and vacation homes because he feared retaliation.

The judge concluded that the deal between Abramovich and Berezovsky was that, in return for substantial cash payments to Berezovsky, Abramovich and Sibneft would enjoy Berezovsky's political patronage and influence, "which was indispensable to the construction of any major business in the conditions of the 1990s."

Gloster wrote that she "could not excuse the extent of Mr. Berezovsky's deviations from his previous case as presented in his pleadings and witness statements. His 'I blame my lawyers" excuse was not convincing. "

"Mr Berezovsky's evidence frequently could not be relied upon, where it differed from that of Mr Abramovich, or other witnesses. I regret to say that," she added.