IAG Chief Executive Willie Walsh said he was confident that Boeing would overcome problems with its 787 Dreamliner jet.

However, he warned said they could take months to resolve.

A series of battery related incidents prompted authorities worldwide to ground the jets and forced deliveries to be delayed.

Mr Walsh said he still considered the 787 "a fantastic aircraft" and expected IAG to take delivery at the end of May of the first of the 24 planes it has ordered.

"I am confident that Boeing will come up with a technical solution to the problems that they have identified," Mr Walsh told an audience at an economic forum at Dublin's Trinity College university.

"I don't know how long it's going to take for them because they will have to do some redesigning of the battery system and I'd expect it to take a couple of months.

"We remain committed to the orders that we've placed with Boeing."

A growing number of investigators and Boeing executives are working to discover the cause of two separate incidents in January involving the 787 that are linked to problems with the jet's battery.

All 50 Dreamliners in service have been grounded while the US National Transportation Safety Board, the US Federal Aviation Administration and other aviation regulators around the world investigate the problems.

No root cause has been identified as yet.

IAG was formed in 2011 by the merger of British Airways and Iberia.

Boeing Co carried out a test flight of its grounded 787 Dreamliner this afternoon in Seattle to collect more data on potential faults in the aircraft's lithium-ion batteries.

The US Federal Aviation Administration said on Thursday it would allow 787 test flights, under more stringent rules, to monitor the batteries in flight.