* Investors include SoftBank, Mubadala -sources
* New round values firm over $50 bln
* Says new funds for AI, global expansion (Adds SoftBank confirmation, updates sourcing on Mubadala investment)
BEIJING, Dec 21 (Reuters) - Chinese ride-hailing firm Didi Chuxing Technology Co on Thursday said it has raised $4 billion in funds earmarked for expansion overseas and into areas such as artificial intelligence (AI), as it looks to challenge Uber Technologies Inc.
The fundraising values Didi at over $50 billion and involved Abu Dhabi state fund Mubadala Capital, two people familiar with the deal told Reuters. Mubadala did not respond to a request for comment.
Existing investor SoftBank Group Corp also participated in the latest funding, a spokesman for the Japanese firm confirmed, declining to specify the size of its investment.
"With a substantial cash reserve, Didi plans to scale up investments in AI talent and technologies," Didi said in a statement. The funds would also help Didi "bring more innovative and diversified transportation services to broader communities around the world."
Didi has expanded overseas rapidly in the past year since sealing its dominance in China with the purchase of Uber's local business in 2016, ending a cash-burning subsidy war that cost the U.S. firm roughly $2 billion.
Earlier this month Reuters reported that Didi was planning to enter Mexico next year, in what would be its first overseas operation not managed through a local partner.
On Wednesday, Didi announced it was looking at entering the Taiwanese market, and had authorized a franchisee operator to do research there on its behalf.
Didi has also invested in several of Uber's rivals globally, including U.S.-based Lyft, Brazil's 99, India's Ola, Singapore's Grab, Estonia's Taxify and Careem in the Middle East.
Besides SoftBank, investors in Didi's previous funding rounds included Apple Inc and Alibaba Group Holding Ltd .
The Wall Street Journal earlier reported the fundraising had pushed Didi's cash reserves to $12 billion from $3.5 billion two years prior. (Reporting by Cate Cadell; Additional reporting by Ritsuko Ando; Editing by Stephen Coates and Christopher Cushing)