US-based online retailer Amazon announced plans to invest $2 billion more in India on Wednesday, after Flipkart revealed the funding of $1 billion the previous day.

Amazon entered India in June and has been employing fresh graduates and launching same-day delivery plans, along with new attractive schemes, to boost their business.

"With this additional investment of US $2 billion, our team can continue to think big, innovate, and raise the bar for customers in India. At current scale and growth rates, India is on track to be our fastest country ever to a billion dollars in gross sales," Jeff Bezos, founder and CEO of Amazon, stated in a press release.

"A big 'thank you' to our customers in India - we've never seen anything like this," he added.

Amazon on Monday said it will increase its presence in the country by coming up with five more warehouses, and almost doubling its storage capacity to half a million square feet.

"It's all about who builds up scale faster and remains relevant for the next few decades," Reuters quoted Harminder Sahani, managing director of retail consultancy Wazir Advisors.

Indian online retail business is expanding at an annual growth rate of 34 percent. Amazon sold goods worth $1.6 billion last year and it is expected to touch a revenue of $76 billion by 2021, according to research firm Forrester and Technopak.

Earlier this month, the Indian government had proposed allowing FDI in retail during union budget presentation. Finance Minister Arun Jaitley proposed allowing foreign retailers, who manufacture products in the country, to sell through online platforms, a step towards easing overseas investment in the country's $13 billion e-commerce industry.