The travel plans of hundreds of angry passengers have been disrupted since the technology broke down on Wednesday.

Last night flights were running around 20 minutes behind schedule due to the continued difficulties at air traffic control.

The Irish Aviation Authority said the airport was currently operating at 80% capacity and that would continue over the weekend.

“I appreciate there will be delays for people,” said IAA spokeswoman Lillian Cassin.

“We apologise to customers and to the travelling public because of that, but every decision we have taken over the past two days has been taken in the interests of safety, because above and beyond everything else we must deliver a safe service.

“At this stage we don’t know when we will get back up to 100%. It is likely that we will stay at 80% or so over the weekend. We will gradually increase. We will obviously increase to 100%.”

The airport increased the number of arrivals per hour from 16 to 20 arrivals which will reduce the level of delays. Ms Cassin pointed out that general delays were common with air traffic control systems across Europe.

She also defended the IAA against claims of not providing enough information to passengers: “All I can say is that we are doing our very best to communicate with the public through press releases, through information on our website, personally I have been talking non-stop about this to the media,” she said.

“A dedicated customer management team has been communicating with customers, the airlines.”

The radar system was installed at Dublin Airport in 2003 at a cost of 115 million euro (£91.5 million).

Ryanair chief executive Michael O’Leary called for air traffic to be diverted to Shannon Airport.

But Ms Cassin said passengers could pursue the issue of compensation with the Commission for Aviation Regulation or their travel insurers.