An autonomous Robo Minibus jointly developed by Renault and WeRide undergoes a test in Barcelona, Spain, on Feb 14. JOSEP LAGO/AFP

Driverless cars have moved a step closer to becoming a reality on the roads of Europe after 17 countries signed a joint declaration regarding a coordinated cross-border approach to autonomous vehicle testing.

Driverless taxis are already used on the streets of more than two dozen cities across China and the United States, but differing national policies have so far held up progress in Europe.

Now, seven years behind schedule, it looks like things could soon be moving after transport ministers from countries including France, Germany, Italy, Poland, and Sweden put their signatures to a document establishing a common testing framework.

Autonomous vehicle expert Herve de Treglode said progress had been held up in Europe by the existence of a developed public transport network and also by regulatory issues, such as the current requirement for a non-intervening "safety driver" to be on board. But he also said he believed robotaxis could be in commercial use as early as next year.