Ryanair shares see-sawed in Dublin before finishing down after rumours of a settlement with the European Commission in relation to subsidies and incentives received at Charleroi airport were scotched.

The shares rose strongly yesterday morning on foot of weekend reports that the low fare airline had reached a "working agreement" with the Commission. By lunchtime the shares had gained 23 cents to €6.15 but when Ryanair and the Commission both dismissed the report, the shares slumped and ended the day at €5.80, 19 cents lower than its opening price of €5.92.

The Commission's spokesman on transport affairs said he had no knowledge of any agreement. He added that the investigation was in the "final straights" and a decision is expected by the end of October.

Ryanair also said no deal had been agreed. Its head of communications, Mr Paul Fitzsimmons said: "Ryanair knows of no such agreement, and would strongly welcome an early and positive decision from the Commission which will promote competition, choice and lower fares for European consumers."

Analysts have been suggesting that a positive outcome for Ryanair could add up to one euro to its share price.

The Commission's investigation could force the airline to repay the many millions of euro it received in subsidies and incentives at Charleroi in Belgium as part of a deal struck two years ago.

It could also shorten the length of that deal which was struck to cover 15 years. Airline chiefs across Europe have been complaining to the Commission about the subsidies being doled out to the airline by publicly-owned airports to attract its business.