LONDON (Reuters) - One of the “Chennai Six” group of ex-British soldiers jailed in India was dragged to a psychiatric hospital and force-fed anti-psychotic tablets during his time in jail, a London court considering whether to extradite Indian tycoon Vijay Mallya was told on Thursday.

Vijay Mallya arrives at Westminster Magistrates Court in London, Britain, December 4, 2017. REUTERS/Simon Dawson

Mallya, 61, is wanted in India on fraud and money-laundering charges relating to his defunct Kingfisher Airlines and Indian authorities want to recover about $1.4 billion they say Kingfisher owes.

The businessman, co-owner of the Force India Formula One team, who moved to Britain in March last year, says the case him is politically motivated and is fighting extradition on several grounds including a claim that jail conditions in India are incompatible with British human rights laws.

As part of this, his lawyer quizzed prison conditions expert Dr Alan Mitchell about a conversation he had had two days ago with one of the former British soldiers who had been held for four years in India on weapons-smuggling charges after the vessel they were working on strayed into Indian waters in 2013.

The soldiers were released from jail in Chennai, eastern India, after a successful appeal and began arriving back in Britain last week.

The ex-soldier, named only as “A”, said he had been grabbed by 15 prison guards and prisoners and taken to a psychiatric hospital because he had been “excessively walking” around the prison, Mitchell told London’s Westminster Magistrate Court.

“While in the psychiatric hospital, he stated he was tied up, gagged, he was beaten and he was forcibly injected. In addition he described being force-fed anti-psychotic tablets that he managed to spit out,” Mitchell said.

Asked by Mallya’s lawyer Clare Montgomery about assurances given over the treatment of Mallya, who she said had diabetes, coronary artery disease and sleep apnoea, Mitchell said the British government had likewise told parliament that the Chennai Six were being well looked after.

“Despite assurances having been given in parliament, ‘A’ was extremely disappointed by what effect the involvement of the High Commission and the UK government had on conditions in which he and his fellow prisoners were held,” he said.

Mark Summers, the lawyer representing the Indian government, said Mitchell’s evidence involved an uncorroborated account which could be used as a “platform for a compensation claim against the UK government”.

He said conditions in Chennai would bear no relation to the jail in Mumbai where Mallya would be held.

Another hearing in the London extradition case against Mallya will be held on Jan. 10 with a decision expected at a later date.