Indian police on Tuesday launched a major hunt for one of the country's richest men, coffee tycoon V.G. Siddhartha, amid mounting fears for his safety.

The billionaire owner of the Cafe Coffee Day chain that beat Starbucks at its own game in India was last seen on Monday night walking across a bridge in the southern state of Karnataka.

His chauffeur alerted police when Siddhartha did not return.

Police divers, backed by local fishermen, searched the Nethravathi river near Mangalaru whilst senior Karnataka politicians flocked to the tycoon's home.

Siddhartha's family has been in the coffee business for more than 130 years.

On taking it over, he set up the Cafe Coffee Day chain in 1996 and also became one of the world's biggest coffee traders, as well the as owner of Asia's biggest coffee plantation.

Siddhartha owned about 12,000 hectares (30,000 acres) of plantations and his Amalgamated Bean Company (ABC) is India's largest exporter of green coffee.

Cafe Coffee Day has more than 1,700 stores, mainly in India, but also in Malaysia, Egypt, Czech Republic and Austria. US giant Starbucks has so far managed to open just over 150 stores in India.

Siddhartha married a daughter of S.M. Krishna, a former foreign minister and chief minister of Karnataka, making him one of the country's best-connected tycoons.

But his empire came under pressure after the tax authorities launched raids on company offices in several cities in 2017. Reports said Siddhartha was in talks with Coca Cola about selling a major stake.

Several media quoted from a letter Siddhartha sent to company shareholders on Monday which said: "I am very sorry to let down all the people that put their trust in me.

"I fought for a long time but today I have given up as I could not take any more pressure from one of the private equity partners forcing me to buy back shares."

Siddhartha, who is aged about 60, left Bangalore on Monday night at first telling his family he was going to the hill resort of Saklesharm, reports said.

Police told reporters that he told his driver to go to Mangaluru instead.

The driver was ordered to stop on a bridge near Mangalaru and he got out whilst talking on the telephone.

Coffee Day Enterprises shares fell heavily on the Mumbai stock exchange after the company confirmed that its chairman "is not reachable since yesterday evening" and authorities had been alerted.

The firm vowed it would "ensure continuity of business".