The UK is trying to resolve as quickly as possible the “confidential” legal issue holding up the extradition of fugitive businessman and former member of parliament Vijay Mallya to India, Britain’s acting high commissioner Jan Thompson said on Tuesday.

Extradition proceedings against the liquor baron concluded in May after the UK high court rejected Mallya’s plea to approach Britain’s Supreme Court against the move to send him back to India, but the secret proceedings have held up his departure.

Asked about the matter at a virtual news briefing, Thompson said it wouldn’t be possible for her to provide a precise timing for Mallya’s extradition. “I think you are probably aware, because we’ve said it a number of times, there is a further legal issue that needs resolving before we would be in a position to extradite Mr Mallya.”

She said the extradition had “been ordered some time ago”, and it was “difficult for me to comment on it very substantively” because it is a legal matter.

“But the extradition cannot take place until that particular legal issue is resolved. It’s a confidential issue, I can’t say any more on it. Nor can I estimate how long it will take to be resolved, but what I can is that we’re trying to resolve the issue as quickly as we can,” Thompson said.

India has already said it is not a party to the “secret legal matter” in the UK that has held up Mallya’s extradition. External affairs ministry spokesperson Anurag Srivastava told a news briefing in October that the secret legal matter “is yet to be resolved, and that without its resolution, he cannot be extradited”.

“We are not a party to this matter and we continue to be in touch with the UK government,” Srivastava had said at the time.

The UK magistrate’s court recommended Mallya’s extradition on December 10, 2018. Mallya’s appeal against this order was dismissed by the UK high court on April 20 this year.

Mallya then applied to the UK high court for leave to appeal in the Supreme Court and it was rejected on May 14. He has exhausted all avenues for appeal.

There has been speculation in London that the most likely issue holding up Mallya’s extradition was an application for asylum, a process on which British authorities do not publicly comment on individual cases as a matter of policy and strict data protection laws.

Mallya flew to the UK in March 2016 as a consortium of Indian banks, which claims he owes Rs9,000 crore in principal and interest on loans extended to his defunct Kingfisher Airlines, closed in on him to recover the money. He was subsequently declared a wilful defaulter in India.