* Commission had concerns over insufficient competition
* IAG agrees to release five daily slots at London Gatwick
* EU approval follows backing from main shareholders (Adds details, quote)
DUBLIN, July 14 (Reuters) - IAG has gained European Union antitrust approval for its 1.3-billion-euro ($1.4 billion) bid for Irish carrier Aer Lingus after agreeing to make concessions to ease competition worries, the EU Commission said on Tuesday.
IAG's plan to buy Aer Lingus and build a new transatlantic hub at Dublin airport won the support last week of Ryanair, which holds a 30 percent stake in its rival, after convincing the Irish government to sell its 25 percent stake in May.
Reuters reported on Friday that British Airways-owner IAG was set to win approval after improving concessions, including giving up some airport slots in London and agreeing to special agreements with rivals, clearing the last hurdle for a takeover that dragged on for months.
"These commitments adequately address all competition concerns identified by the Commission," the Commission said in a statement.
The Commission said it had concerns that the merged entity would have faced insufficient competition on several routes and that it would have also prevented Aer Lingus from continuing to provide traffic to the long-haul flights of competing airlines.
It confirmed on Tuesday that IAG had submitted commitments to release five daily slots at London's Gatwick airport to facilitate the entry of competing airlines on routes from London to Dublin and Belfast.
IAG also made a commitment to enter into agreements with competing airlines which operate long-haul flights out of Britain, the Netherlands and Ireland so that Aer Lingus will continue to provide these airlines with connecting passengers.
Ireland's transport minister welcomed the decision and said officials would review it in order to confirm that there is no impact on the connectivity commitments the government agreed with IAG to win sceptical MPs over.
Adding Aer Lingus to its portfolio of airlines - British Airways (BA), Iberia and Spanish budget carrier Vueling - opens a new avenue of growth for IAG, allowing it to expand capacity on lucrative transatlantic routes by using Dublin Airport. ($1 = 0.9083 euros) (Reporting by Padraic Halpin; Editing by Pravin Char and Susan Thomas)