Mumbai, Oct. 23: Ratan Tata, chairman emeritus of Tata Sons, has made an investment in US-based start-up Abra.

Abra, an entity dealing in digital currency, announced that it has received strategic investments from Tata and American Express as part of a Series A round. These are the first investments in the crypto currency world for both American Express and Ratan Tata, Abra said in a statement issued on Thursday.

The firm also announced its entry into online, digital cash-based merchant payments. Abra's app will be available to all registered users in the US and the Philippines in the coming weeks with more countries to follow soon, it added.

"Tata and American Express have made strategic investments in Abra as part of a recently announced Series A round. These are the first investments in the crypto-currency world for both American Express and Ratan Tata," Abra said.

Crypto-currency is a digital or virtual currency, which uses cryptography for security. It is also difficult to counterfeit. The first crypto-currency to garner global attention was Bitcoin, which was launched in 2009.

Using the Abra app, users can store digital cash and can send the money to any smart phone. It uses a new network of human ATMs called Abra Tellers, who are individuals or businesses earning money by buying and selling digital cash to and from any consumer via the app. The firm has already begun signing up merchants for this new solution.

Abra according to its website is a digital cash, peer to peer money transfer network, which represents a global network of consumers helping each other easily deposit and withdraw cash from the Abra app anywhere in the world. Founded in 2014 by Bill Barhydt, it is based in Silicon Valley, California.

The company had in September announced the closure of its Series A financing round, which raised over $14 million in venture financing. Investors in the Series A financing round included Arbor Ventures, RRE Ventures and First Round Capital.

Tata, in his personal capacity, has so far invested in more than a dozen start-ups, most of whom are technology driven. Recently he had invested in Holachef, an online marketplace for chefs.

Some of his investments include the online furniture company Urban Ladder, online jewellery retailer Bluestone, Chinese smartphone maker Xiaomi and CarDekho, the auto classified portal among others. Last year, Tata has also put money in his personal capacity in Snapdeal, the online marketplace.