KYIV, Sept 18 - 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.