Armed men posing as officials from India's central bank have robbed a vehicle transporting 70 million rupees ($800,000; £600,000) in the southern state of Karnataka, police say.

A massive operation has been launched to find the men who robbed the van in the heart of Bengaluru city in daylight.

The robbery occurred on Wednesday afternoon when six men in an SUV stopped a cash-transport van on a busy road as it was moving money between bank branches, Bengaluru police commissioner Seemant Kumar Singh told the BBC.

The van was carrying a driver, a cash custodian, and two armed security guards.

Mr. Singh says the robbers told the people in the van that they were officials from the Reserve Bank of India and needed to verify if they had the correct documents to transport such a huge amount of money.

The gang instructed the cash custodian and guards to leave their weapons in the van and board the SUV, while the driver was told to continue driving with the cash, according to police.

The SUV followed the cash van for a few kilometers before the gang forced the driver out, made the cash custodian and guards exit the vehicle, transferred the cash at gunpoint, and fled.

With little CCTV coverage in the area, police are examining whether multiple vehicles were involved in the operation.

The cash transportation service company has filed a police complaint and ongoing investigations seek to uncover any potential collaboration from company employees.

The SUV used in the heist had a fake number plate and bore the sticker 'Government of India', as revealed by an anonymous police official. Karnataka Chief Minister Siddaramaiah stated that the SUV linked to the heist has been recovered, but the exact vehicle used for escape remains unclear.

Home Minister G Parameshwara expressed confidence in the police's ability to resolve the case rapidly, referencing previous successful resolutions of high-profile bank robberies in Karnataka.

In a related incident in May, 59 kilograms of gold worth 532.6 million rupees was stolen from a bank using a duplicate locker key; police have since arrested 15 individuals, including two former employees, and recovered a portion of the stolen gold.