The alleged meeting follows warning from the chief executive of Europe’s biggest carrier by passenger numbers that flights between the UK and EU member states could be put on ice if no deal has been struck by March 2019 when the UK officially exits the EU.

"There is a real prospect, and we need to deal with this, that there are going to be no flights between the UK and Europe for a period of weeks, months beyond March 2019," O’Leary told the European Parliament’s Transport and Tourism Committee last month.

"There is not going to be an interim agreement... we will be cancelling people’s holidays for summer of 2019."

At today’s reported private meeting with Grayling, O’Leary is expected to raise concerns that little progress has been made towards a new bilateral aviation agreement with the EU.

In a statement issued to Sky News, a spokesperson for the Department for Transport (DfT) declined to comment on the alleged talks between Grayling and O’Leary, while Ryanair could not be reached for comment.

The DfT spokesperson added: "Aviation is absolutely crucial to the UK’s economy and we are committed to getting the right deal for Britain.

"Our aviation industry is the largest in Europe, and both we and the EU benefit from the connectivity it provides.

"That’s why we are pursuing liberal access to European aviation markets - including all the benefits that brings for consumers."‎

According to Sky News, a source said that the agenda for the meeting was "a regular catch-up" and would not only cover Brexit-related matters.