Uber CEO Travis Kalanick Flickr via Heisenberg Media Baidu, China's largest search engine company, confirmed on Wednesday morning an investment in ride-sharing app Uber. A China-based Bloomberg reporter tweeted a picture of the signing ceremony in the early hours of Dec. 17.

The investment, reported on Dec. 12 by Bloomberg to be worth as much as $600 million, will buy a minority stake in Uber and give the startup a huge lift as it looks to expand its operation in China, a person familiar with the matter told the website. The deal brings cash and non-cash assets, including Baidu's online resources, the source said.

The deal was agreed at Baidu HQ in Beijing. Baidu chairman and CEO Robin Li and Uber's CEO Travis Kalanick were both there.

In a statement on TechCrunch, Kalanick said:

"This collaboration marks a milestone for Uber. We're currently in 250 cities around the world, and the Asia-Pacific region has been a key area of growth for us. Our partnership with Baidu — a premier global brand — reflect our commitment to the region and the growing community of Uber riders and driver partners here."

Here's the deal being confirmed. Instagram/allenpenn

TechCrunch explains the move will allow Uber to make use of Baidu's app distribution channels, which it bought for $1.9 billion in 2013. It means the company can take advantage of Baidu Map, an interactive heat map of peoples' travel patterns with more than 240 million monthly users. The US company will be hiring in 14 cities in the world's most populous country.

Uber has now received £3.3 billion in 8 rounds of funding from 37 investors, CrunchBase figures reveal. Last time the San Francisco taxi-booking service was valued it came in at $40 billion — and the most recent will no doubt send its valuation even higher, though it remains unclear by exactly how much. Still, Uber is now said to be worth four times as much as other big Silicon Valley startups, and nearly double that of Tesla.

Since 2009 alone, Uber has now raised $2.5 billion. It is continuing to roll out ventures across the world, despite regulatory hurdles. Indeed, it appears Uber is truly an unstoppable force.