Online grocer Ocado has won the first round in a patent-infringement case filed in the US by rival AutoStore.

Three AutoStore patents are invalid, while Ocado does not infringe a fourth, US International Trade Commission Judge Charles Bullock ruled.

The decision will still have to be reviewed by the commission and the final verdict is expected to be released in April.

If negative, it could hamper the expansion of the FTSE 100 group into the US market as it may block or limit the types of robots that can be brought into the country.

Ocado commented: “This was a misconceived attempt by AutoStore to interfere with our business in the United States.” 

The companies have been quarreling over patents in various jurisdictions since 2016 but the battle heated up just before Ocado signed an agreement for its platform with Kroger, one of the biggest US supermarket chains. 

AutoStore, which started in the 1990s with a vertical grid robotic warehouse system, says its technology forms the basis of Ocado’s business-to-business platform. 

Ocado’s value has soared by over 400pc since 2016, as traders bet it will be the top company in the global online grocery sector.

At some point it surpassed the market capitalisation of Tesco, the UK’s largest supermarket chain, even though Ocado only has a fraction of its market share and has barely made a profit in more than two decades of operation. 

It started as the online delivery partner of Waitrose, but it then repositioned itself as a technology company that can provide a logistics and distribution platform to license to retailers around the world. 

Marks & Spencer is currently the main partner for Ocado’s grocery website, having bought a 50pc stake for £750m two years ago.