Etihad Airways has increased its stake in Aer Lingus to more than 4 per cent.
The Gulf carrier has this month made share purchases to up its holding in the Irish airline from 2.99 per cent to 4.11 per cent.
An Etihad spokesman said: "Etihad Airways' stake in Aer Lingus now exceeds 4 per cent following the acquisition last week of further shares on the open market.
"The airline has therefore notified the Central Bank of Ireland accordingly."
Etihad's stake in Aer Lingus now stands at a little under 37 million euros.
Irish Stock Exhange rules require Etihad to disclose its shareholding in the airline once it passes 3 per cent and beyond.
Last year, Etihad secured approval from US regulators to codeshare on Aer Lingus transatlantic flights from Dublin (see news, April 2013).
It bought its initial 2.987 per cent stake in Aer Lingus in 2012 (see news, May 2012).