that Didi was in talks to raise a new round of money on Wednesday. On Friday, a source familiar with the matter told CNBC that the latest funding round values Didi at $50 billion.

Didi said the round will be used "to support its global strategy and continued investments in AI-based technologies," in a statement.

Chinese ride-hailing giant Didi Chuxing , the company that bought Uber's China business last year, has closed a $5.5 billion funding round, valuing the company at over $50 billion, making it one of the world's most valuable private technology companies.

This makes it on of the largest private technology companies behind Uber which is worth around $66 billion and Alibaba's payment affiliate Ant Financial, which is worth $60 billion.

Didi declined to disclose the investors in the latest round or its valuation when contacted by CNBC. But sources told CNBC that previous backers Softbank, Bank of Communications, China Merchant Bank are involved, with Silver Lake being a new addition.

Uber and Didi were in an intense battle in China until last year when the Chinese firm bought the U.S. ride-hailing app's business in the world's second-largest economy. At the time, this valued the company at $35 billion. The latest valuation is significantly higher. Uber has a roughly 20 percent stake in Didi as a result of the transaction.

Didi founder and chairman, Cheng Wei, holds a non-voting seat on Uber's board.

The company has some high-profile investors including Chinese e-commerce giant Alibaba, iPhone maker Apple and venture firm DST Global.

Didi has been expanding aggressively and has even invested more than $1 billion in U.S. Uber rival Lyft. Didi's president Jean Liu has said the company is "definitely going global" — and that inevitably means challenging Uber in other markets (like Brazil, where it announced a "strategic investment" in ridesharing startup 99 in January).

Didi's latest mega-round would give the company more firepower to boost its presence in China and beyond.

The start-up has also been investing in new technology, particularly artificial intelligence. In March, it launched Didi Labs in Mountain View, California — a research and development center aimed at boosting its AI capabilities. The latest funding round will help Didi in its AI efforts.

"Building on its competitive AI-based analytics capabilities, Didi is working towards systemic breakthroughs in intelligent driving technologies and smart transportation architecture," the company said in a statement.

CNBC's Deirdre Bosa and Sally Shin contributed to this report.