(Reuters) - The European Tour has had to close ticket sales for an event for the first time after the final two rounds of next week's Irish Open were sold out.

The tournament's return to Royal Portrush for the first time since 1947 has attracted a field including world number two Rory McIlroy and fellow Northern Irishmen Darren Clarke and Graeme McDowell.

Triple major champion Padraig Harrington and U.S. PGA winner Keegan Bradley are also due to take part in the June 28-July 1 event in County Antrim.

"We are preparing for a crowd around the 100,000 mark for the week...and with a particularly large spectator audience expected for the weekend we felt it prudent to stop selling tickets for Saturday and Sunday," championship director Antonia Beggs said in a news release on Thursday.

Portrush is the home town of Clarke who claimed his first major victory in the British Open at Sandwich last July.

(Writing by Tony Jimenez; editing by John Mehaffey)