Ryanair is in early discussions with Airbus about a future order for some 100 A321 aircraft for its recently acquired subsidiary Laudamotion, Chief Executive Michael O'Leary said on Wednesday.

The Irish budget carrier is also interested in the latest Boeing narrow-body model - the 737 MAX 10 - for its all-Boeing main fleet "at the right price" but those conditions do not exist currently, O'Leary told Reuters in an interview.

Any future order of Airbus A321s for Austrian unit Laudamotion would most likely not include fewer than 100 aircraft, O'Leary said on the sidelines of an A4E airlines conference in Brussels.

"With Airbus we are talking about the possibility of A321s for Laudamotion but that is at the very initial stages," O'Leary said.

Asked how many aircraft might be involved, he said, "I would not see any point in having an order if it is less than 100 aircraft - 50 firm and 50 options."

Such an order would be worth at least US$6.5 billion at current list prices.

Ryanair - which has stuck to Boeing for its main fleet to become one of the U.S. planemaker's biggest customers - sees the relationship with Laudamotion as a source of flexibility as weakness among some carriers produces potential new targets.

"We are committed to being an Airbus customer through Laudamotion because in the future, as there are competition divestments or other M&A opportunities in Europe, some will be on the Airbus side and some will be on the Boeing side and we want to be able to do both," O'Leary said.

For its main fleet - which O'Leary said would continue to remain exclusively Boeing - the Irish executive said Ryanair would be interested in Boeing's new 737 MAX 10.

"When there is an opportunity to do a deal on pricing - and that doesn't exist at the moment - we would certainly look. The next likely follow-on order with Boeing would be the MAX 10 aircraft. We need to go up to 230 seats," he said.

Ryanair is not however interested in a potential larger, mid-sized aircraft whose development is being studied by Boeing.