By Aditya Soni (Reuters) -Tesla shares jumped 10% on Monday, lifted by the long-awaited launch of the company's robotaxi service that CEO Elon Musk has for years championed as a key driver of the electric vehicle maker's lofty valuation.

The service kicked off as scheduled aboard Tesla's Model Y vehicles, with customers paying a $4.20 flat fee to ride.

Analysts said the "low-key" robotaxi launch highlights Tesla's big bid to compete with existing self-driving taxi operators in the US and China, as the sector grows. Musk congratulated Tesla's artificial intelligence and chip design teams on the launch in a post on X, writing that it was "culmination of a decade of hard work".