Seven people have been arrested in India after a daring 70m rupees ($800,000; £600,000) heist in which armed men posing as central bank officials robbed an ATM cash van.

On Saturday police in the southern city of Bengaluru said they had cracked the case and recovered 57.6m rupees of the money stolen three days earlier.

Bengaluru police commissioner Seemant Kumar Singh told the BBC on Sunday that a seventh man had been arrested in Bengaluru, adding it would take time to determine the amount of money "in his possession."

Singh said the police are still looking "for two or, maybe, three more," suspects.

Those arrested include Gopal Prasad, an employee of cash transport company CMS, J Xavier, a former CMS worker, and Annappa Naik, a local police constable.

The robbery took place in broad daylight in the Lalbagh area of Bengaluru. 

The thieves pretended to be officers of the Reserve Bank of India. They stopped the transport vehicle saying they had to check the paperwork for such a large amount of money.

The vehicle's cash custodian and two security guards were instructed to get into an SUV, while one of the gang members took control of the van, police said.

Police said the gang had changed vehicles, used fake registration plates and selected locations with minimal CCTV coverage to transfer the boxes of cash.

A massive hunt was launched on Wednesday, with more than 200 police officers deployed across Karnataka state and the neighbouring Kerala, Tamil Nadu, Telangana, Andhra Pradesh and Goa states.

Detectives are investigating the role of CMS and possible violations of guidelines for transferring cash, Singh said.

"The vans should not follow the same route and timing repeatedly so as to become predictable,'' he added.