EU travellers who book flights through a European airline can claim compensation in the event of a major delay of the connecting flight -- even outside Europe, a court ruled on Thursday.

In its judgement, the European Court of Justice said that the entirety of a journey that was subject to a single reservation fell under the EU's rules on flight delays, even if the flight was operated by a non-EU airline.

The case involved a journey booked through German carrier Lufthansa for three passengers from Brussels to San Jose in California, with a stopover in Newark.

The passengers arrived in San Jose with a delay of 223 minutes and over the three hours that guarantees inconvenienced travellers a right for compensation under EU rules.

The flight was entirely operated by United Airlines, and the Luxembourg court said the US airline was on the hook to compensate the three passengers since the journey began in Belgium, an EU member state.

The decision confirmed that the passengers were eligible to receive the maximum amount compensation of 600 euros ($650) each under the rules.