SEATTLE • Microsoft Corp has agreed to invest about US$100 million (S$137 million) in Uber Technologies at a valuation of approximately US$50 billion, a source said. The deal was finalised earlier on Friday, said the source, who asked not to be identified.

Uber, which was previously valued at US$40 billion when it raised financing earlier this year, is benefiting from investors which view its car-booking technology as the future of transport. The San Francisco-based company, led by chief executive officer Travis Kalanick, is using the cash to expand operations to cities across the globe.

"We filed to authorise this new funding more than two months ago," said Uber spokesman Kristin Carvell. "The filing is available to the public. We aren't commenting on additional speculation."

Mr Tony Imperati, a spokesman for Redmond, Washington-based Microsoft, declined to comment. The Wall Street Journal earlier reported that Uber closed a US$1 billion financing round at a valuation of about US$51 billion, and that Microsoft participated in the deal.

Microsoft last month sold a portion of its Bing mapping unit to Uber, which offered positions to about 100 Microsoft employees who work on image acquisition and data analysis as part of the mapping team for Bing, Microsoft's Web-search engine.

The two companies have also combined to integrate Uber into Microsoft's Cortana voice-controlled assistant so that it can hail an Uber ride for users as a scheduled meeting on their calendar approaches. An investment, if it happens, would be a recognition that the two companies, which have worked together in the past, plan to remain partners, the source said.

Uber, founded in 2009 by Mr Kalanick and Mr Garrett Camp, has expanded to more than 300 cities in at least 57 countries. It has upset regulators, who have sued or banned the company from California to Brazil. BLOOMBERG