Aer Lingus says that damage caused to a fibre optic cable during construction work led to Saturday's IT outage which resulted in the cancellation of more than 60 flights.

In an email to affected customers this evening, the Aer Lingus CEO Lynne Embleton has once again apologised for the disruption and outlined what happened.

"Aer Lingus has a contract with a leading cloud services provider to host the network and infrastructure behind our core operational and customer system," Ms Embleton wrote.

"Their internet service provider in the UK had a major failure in their network when, early on Saturday morning, unrelated construction work damaged one of their fibre optic cables which provides connection to our systems. The cable was not repaired until 5.30pm and at that point, our Aer Lingus systems began to come back on-line.

The IT outage affected thousands of Aer Lingus passengers last weekend

"Of course, the question we have asked our supplier is what happened to the back-up which should have kicked-in and supported our systems. And the answer is that, unfortunately a component then failed in the back up.

"This should not have happened and our supplier has apologised for both the break in the main connection and the failure in the back-up.

"Both have now been fixed and measures have been put in place which should prevent an outage of this type happening again," Ms Embleton wrote.

The travel plans of thousands of Aer Lingus passengers were disrupted last weekend with some customers having to wait days to complete their journeys.

Many of those impacted complained about Aer Lingus customer service and communications.