When he returns to India, he will likely be held in the capital's high-security Tihar jail.

His capture is thought to have been orchestrated by Ajit Doval, national security adviser to Indian Prime Minister Narendra Modi and has been hailed as a "major achievement" by local media.

A close associate of Dawood Ibrahim, a gang boss who is currently India's most wanted fugitive, Rajan made huge sums from extortion rackets targeting the Bollywood film industry.

After fleeing India toward the end of the decade, he evaded authorities and continued his criminal career in Thailand, Indonesia and Australia, where he was living under a fake Indian passport until last week.

The impending arrival of Rajan in India has also prompted a turf war between India's security agencies, with officials in Delhi indicating that they do not have full confidence in Mumbai's police force. Gangs in the city are known for having close relations with some corrupt officers.

However, Mumbai police chiefs have insisted that Rajan, who is reported to be unwell, should be handed in to their custody to face trial for dozens of crimes in their jurisdiction.

Complicating the case further is the possibility that Rajan has been a source of information for Indian intelligence services, primarily on the whereabouts and operations of his former associate Ibrahim.

In 2005, Doval, a former intelligence chief before being appointed national security adviser last year, was found by Mumbai police in the company of key aides of Rajan when they intercepted a car in Delhi.

There have been reports in India that Rajan gave himself up to Indian authorities as part of a deal. In a profile in the newspaper, security reporter Josy Joseph said Rajan was seen as "the patriotic don".

In recent years, the infamous gangs of Mumbai have lost much of their power, with legal industries such as construction replacing drugs and extortion as the preferred way for many criminals to earn significant sums of money. The killing of many gang members by specialist police "encounter" squads was also a factor in their decline.

"His network was finished around 10 years back. He had so many millions but his lieutenants left him because he killed his own men," said Sachin Vaze, a former anti-gang police officer.

Rajan retained some influence in Mumbai, however, and was alleged to have been linked to the killing of a high-profile journalist, Jyotirmoy Dey, in 2011.

Recently there has been a surge in gang activity in Mumbai targeting the film industry in an effort to find a "new business model", police in the city said.

Investigators intercepted communications indicating gunmen have been told not to hurt film stars but simply scare them.

Experienced observers of the Mumbai crime scene said that as "big guys have pretty much retired", the extortion efforts directed at Bollywood celebrities were the work of "desperadoes trying to establish themselves and cash in on the fear factor".

Rajan's relations with Ibrahim, a Muslim, soured and a definitive split came after a series of bombings in Mumbai in 1993. According to a 2005 US diplomatic cable, Rajan reportedly objected to the attacks, which had been planned by Ibrahim following the destruction of the Babri Masjid mosque by Hindu extremists the previous year.

"For me [Rajan] was never a real don," Vaze said. "He was always the petty criminal, a black marketeer. He was always No 2."

*A caption that referred to Rajan's passport as Indonesian was incorrect. He was carrying a fake Indian passport.