Etihad Airways has acquired a 2.987% stake in Aer Lingus.
The airline said the purchase reflected its "desire to forge a commercial partnership with the Irish national carrier".
Etihad said it believes a possible partnership could produce "significant commercial benefits for both airlines".
Last year, Etihad increased its 2.99% stake in Air Berlin to 29.2% via the purchase of €73 million of new shares.
Industry observers believe it could do the same with Aer Lingus once the Irish government puts its 25% stake up for sale.
But according to the Financial Times, analysts say the 25% stake cannot be sold until a solution is found to a €700 million hole in a pension fund for staff and former employees of Aer Lingus and Dublin airport.
Further details on this issue are expected to be announced when Aer Lingus issues a trading statement on Thursday.
In addition to its stake in Air Berlin, Etihad also owns 40% of Air Seychelles and is reported to have been investigating a partnership with Air France KLM.
Etihad Airways operates 10 flights a week from Abu Dhabi to Dublin and has carried more than 750,000 passengers between the two capitals since it began flying the route in July, 2007.
The airline has a premium lounge at Dublin Airport, an engineering maintenance facility and has conducted recruitment drives across the country.
It also recently renewed its sponsorship of the Gaelic Athletic Association, signing a five-year deal.
Etihad Airways has strategic codeshare partnerships with 34 airlines around the world.
