Ireland's Ryanair airline is planning aggressive expansion in Ukraine if the country joins the European Union's Open Skies deregulated aviation market in the coming months, Reuters has reported, referring to Group Chief Executive Michael O'Leary.

"The one market I would point to is Ukraine... I would think we will be a major investor in Ukraine when they join up to European Open Skies," O'Leary told an investor call following the company's annual general meeting.

He expected the Ukrainian government to sign up to Open Skies before the end of the year.

O'Leary said Ryanair currently operates from five Ukrainian airports on a bilateral basis but that there were as many as 12 suitable airports in the country.

Migrant workers would provide a major market for Ryanair's fares, which he said currently average around EUR 40 per flight.

The airline also sees potential in the country's domestic market.

"I think that will be certainly a model that we will be aggressively moving into," O'Leary said.