Spanish taxi drivers demanding more regulations for app-based ride-hailing services blocked access to a trade exhibition centre in Madrid where a major tourism fair was on.

Riot police trying to clear a blocked highway circling the Spanish capital briefly clashed with the drivers on Wednesday, many wearing the yellow traffic safety vests used by protesters in neighbouring France.

Taxi drivers clash with policemen in Madrid. Photograph: Anadolu Agency/Getty Images

The protesters allowed a convoy carrying King Felipe VI and Queen Letizia of Spain to enter the exhibition centre where the royals opened Fitur, one of the main fairs for the global tourism industry.

Other authorities, exhibitors and guests used public transportation to reach the premises.

The drivers say they will continue their open-ended strike until regional authorities in Madrid agree to a solution like the one offered on Tuesday in Spain’s second largest city, Barcelona. Under the pressure of a week-long strike there, the Catalan regional government wants to force users of apps like Uber and Cabify to contract rides one hour in advance.

Madrid’s conservative regional chief, Ángel Garrido, has refused to take the same step, saying that Barcelona and Catalonia are “heading to the Middle Ages” with such a solution.

Taxi drivers hold a Spanish flag reading ‘Justice’ in front of policemen. Photograph: Javier Soriano/AFP/Getty Images

Cab drivers’ unions in Barcelona also blocked major thoroughfares on Wednesday while discussing whether to accept the terms offered, while the web-based companies are threatening to cease operations in the north-eastern city.

Unauto VTC, the association representing drivers working mostly for Uber and Cabify, said 3,000 jobs were at stake in Barcelona.

In a statement, it said the regional government in Catalonia “has yielded to the blackmail of the taxi drivers, who are again kidnapping the city of Barcelona and using violence to shield their monopoly”.

Previous taxi demonstrations have led to violence. A taxi driver was taken to hospital on Tuesday with a serious head injury as he tried to stop a vehicle.

The protests forced regulatory changes at the national level last year, but Spanish cab drivers consider those insufficient, arguing that their work is regulated as a public service in a way that their competitors is not.