Ryanair has signed an agreement to help China's COMAC develop its medium-range C919 jet for its possible use by the low-cost airline.

Ryanair 'will share its experience and expertise to assist COMAC to develop the new C919 commercial aircraft, with up to 200 seats, which would enable Ryanair to lower costs and continue to lower fares for its passengers across Europe,' the airline said in a statement.

'Ryanair can become a two aircraft operator carrier, as long as the economies achieved by our current Boeing 737-800 fleet can be matched or lowered by a similar sized order from a different manufacturer,' the airline's chief executive Michael O'Leary said.

The C919 - a planned single-aisle jet which can seat up to 190 passengers - is China's first large homegrown passenger jet, and is seen as a potential competitor to the Airbus A320 and the Boeing 737.

'We look forward to its introduction into commercial service from 2018 onwards,' the Ryanair boss said.

Mr O'Leary noted that Ryanair will have a fleet of over 300 Boeing aircraft by 2013, 'and we remain in continuing discussions with both Boeing and now COMAC for a replacement aircraft order of at least 200 aircraft.

While the tie-up with COMAC will not affect Ryanair's relationship with Boeing, O'Leary said increased competition would be good for airlines and would lower the cost of air travel for consumers.