A prison source with knowledge of the remand said the security level on Singh had been raised to the highest of four categories, and he was being kept in a cell for easier and closer surveillance.

“We only keep one or two people in custody in a cell. We hold more than 10 in a dormitory,” the source said. “This allows us easier and frequent observation of a particular person in a less packed cell.”

These measures would limit Singh’s contact with other prisoners, the source added.

“If needed, we will clear corridors for him to pass through to avoid contact or collision with others.”

The source said Hong Kong authorities only discovered Singh was wanted by the international police organisation Interpol when the Post reported on the case on Monday night.

But Terence Lam Kwok-leung, commissioner of the Correctional Services Department, refused to comment on whether the authority had received any prior heads-up.

Indian-born alleged jailbreaker and terrorism funder ‘Romi’ in custody over Hong Kong robbery

“We do not comment on individual cases,” Lam said on Tuesday at an event to present the department’s work in the past year. “We classify people in custody into different security categories based on their previous convictions … and the offences they have, or are alleged to have, committed. Another consideration would be intelligence.”

Lam said the department would decide after a security assessment what measures were needed to ensure a person in custody was being “properly dealt with”.

Indian police said on Friday that Singh had been a middleman coordinating activities between Punjabi gangsters and Pakistan-based terrorists, backed by Pakistan’s secret service.

They also said Singh masterminded a 2016 jailbreak in the Indian city of Nabha in Punjab state. Armed men posing as police officers attacked the high-security prison during the daring escape, freeing a Sikh militant commander and four others.

Lam said preventing prison escapes was the authority’s primary duty and it had a well-established mechanism and response team to handle and escort high-risk inmates.

Interpol launched a worldwide search for Singh after receiving a request from India’s justice department. It was not clear when the request was made.

Among crimes Singh was accused of in the Interpol notice were “conspiring in, abetting, advising and facilitating terrorist activities”, raising funds for terrorism, preparing an act of terror and membership of a terrorist group.

He was also accused of attempted murder, robbery, breaking prisoners out of jail, resisting arrest and rioting, among other crimes.

Interpol said Singh hatched the jailbreak plan “while [inside the prison] in June 2016, and, after his release on bail a month later, fled to Hong Kong, from where he facilitated the daring escape with the help of gangster Gurpreet Singh Sekhon, who was still lodged at Nabha prison”.

“Besides providing money, Romi assured the escapees safe houses and had given his Hong Kong contact number for logistical support,” Interpol said.

The Post reported on Monday that Singh was back in custody after having been out on bail in Hong Kong following charges over another robbery in Hung Hom in March last year involving HK$3.2 million. He was arrested on Wednesday at a roadblock set up by police in Sham Shui Po after the recent robbery in Tsim Sha Tsui.

India has requested he be sent back to face justice.