"While our recovery and growth is very strong, it is still very fragile and is prone to falling over in the case of adverse outside developments," Group Chief Executive Michael O'Leary told a news conference in London.

It "looks like we are on track" to report an average of 4% empty seats per flight for the month of August, the same level as July, he said.

(Reporting by Muvija M; Writing by Conor Humphries)