European regulators on Monday opened the way for air passengers to use mobile phones to talk or text during fights throughout EU airspace as easily as they can on trains.

"From today onwards Europe's sky is open for business by mobile phone operators," said European Commission spokesman Martin Selmayr, "in a blow to those who see air travel as a rare chance to avoid being contacted.

However he stressed that the in-flight service was not yet generally available and so passengers should still heed the advice of flight crews to switch off phones during flights.

At the moment that luxury is limited to a very few travellers for fear of interfering with the aircraft's functioning. Some airlines, notably Air France, have begun testing the system.

Selmayr said that the 27 EU member states have six months to comply with the new rules.

"In-flight mobile phone services can be a very interesting new service especially for those business travellers who need to be ready to communicate wherever they are, wherever they go," EU Telecoms Commissioner Viviane Reding said in a statement.

"However, if consumers receive shock phone bills, the service will not take-off. I also call on airlines and operators to create the right conditions on board aircraft to ensure that those who want to use in-flight communication services do not disturb other passengers," she added.

Selmayr, Reding's chief spokesman, said on-board calls would be "a little more expensive" than those on the ground because the planes will need to install their own in-flight cell phone network.

He told reporters in Brussels however the competitive market place should take care of the price of calls.

"The commission will not interfere with this in the beginning but we will keep a close eye on it," he said.

Asked about the possibility of a plane full of people all chattering away in-flight, he said it would also be up to the airlines to decide how the system is used.

Some airlines are considering only allowing text messages to be sent and received via mobile phones while others may ask passengers to keep their phones on silent mode so that they do not ring.

Selmayr said that safety concerns would be addressed by not allowing phones to be used until planes are at least 3,000 feet in the air.

He also stressed that flight captains would be able to switch off the on-board service if they felt it necessary.

The European Commission is very hopeful that the EU's neighbours and other friendly states from Iceland to Ukraine will agree to adopt the same system so as to extend its reach.

However it won't be available over US airspace where mobile phone calls remain banned and where a different bandwidth is used for cell phones.

The measures announced by the commission will harmonise the technical and licensing requirements for using mobile phones on board aircraft.

Under the system, passengers' phones will be linked to an onboard cellular network connected to the ground via satellite.

The system will at the same time prevent phones from connecting directly to mobile networks on the ground below, thereby ensuring the system does not affect the safety of aircraft or the terrestrial mobile networks.

Harmonising the technical requirements for the safe in-flight use of mobile phones will enable the national licences granted to individual airlines by a member state to be recognised throughout the EU, the commission said.

Therefore an aircraft registered in France or Spain will be able to offer mobile communication to passengers when flying over Germany or Hungary without additional licensing procedures.