Chelsea Football Club owner Roman Abramovich has told a High Court judge that allegations he betrayed a Russian business rival were "wholly without merit".
Mr Abramovich, 45, is being sued for billions of pounds by exiled Russian oligarch Boris Berezovsky, 65, in a trial before Mrs Justice Gloster at the Commercial Court in London.
Mr Berezovsky says the Russian billionaire businessman "betrayed" him and "intimidated" him into selling shares in Russian oil company Sibneft for a "mere 1.3 billion" US dollars (£800 million) - "a fraction of their true worth".
He alleges breach of trust and breach of contract and is claiming more than £3 billion in damages.
However, Mr Abramovich said he owed Mr Berezovsky nothing in "law or honour".
"I would respectfully hope that it will be apparent to this court that Mr Berezovsky's claims are wholly without merit," said Mr Abramovich, in a written witness statement given to the judge.
"Mr Berezovsky has already obtained a very substantial sum of money from me and I do not believe that he has any entitlement to be paid anything more, whether in law or honour."
He says Mr Berezovsky was paid millions of pounds for his services as a "political godfather" but was not a business partner.
The court has heard that Mr Berezovsky "fled Russia, never to return" in late 2000, following a fall-out with then president Vladimir Putin - travelling initially to France then settling in England.
Mr Abramovich gave evidence at the start of his defence case as the trial entered its fifth week. He is expected to be in the witness box for several days.