Eddie Wilson, CEO of Ryanair has said people who are fully vaccinated should be allowed to travel freely.
"There is no reason to lock them up in Ireland any longer," he said.
"A third of our population are double vaccinated. There is no reason for them not to travel. There is no medical reason to stop them from travelling," he added.
On RTÉ's Drivetime, Mr Wilson called on the Government to activate the EU Digital Cert immediately.
He said the system needs to be "switched on" by the Irish Government to allow people to make bookings.
"They should switch it on today, because things just don't light up on 19 July.
"If you want to make a booking and go to another country, you should be able to," he said.
Earlier, Group Chief Executive Michael O'Leary said that as the summer holiday season kicks off, the number of passengers hopping on Ryanair planes is "mushrooming" despite travel restrictions in place to control the spread of the coronavirus.
In an interview with Reuters ahead of a news conference in Lisbon, Mr O'Leary said bookings had recovered very strongly over the last eight weeks, with particularly high volumes of bookings to Portugal and other summer destinations from Germany, Scandinavia, and the Benelux countries.
"Traffic is mushrooming and a lot of that folk are families going on summer holidays to the beaches of Portugal, Spain, Greece and Italy," Mr O'Leary said, adding the airline was on track to fly 80 to 100 million passengers by March 2022.
That is up from 27.5 million last year but still below pre-pandemic levels of 149 million.
Mr O'Leary said Ryanair carried 1.7 million passengers in May and said the number was likely to increase to 5 million in June and 9 million the following month.
Last week, Ryanair launched a legal challenge against Britain over the traffic light system, hoping to force a relaxation of the rules.
Britons returning from European holiday destinations, including Spain, Portugal and Greece, that are currently rated "amber", have to take multiple Covid-19 tests and isolate for 10 days.
Mr O'Leary said the UK and Ireland were opening to travel "more slowly" compared with other countries.
"They are terrified to allow people to travel but I think it will be resolved," he said, adding he believed the UK would join the EU's proposed digital certificate travel scheme, which will potentially be in use by July 1.
Coronavirus cases are on the rise in Britain but also in Portugal, particularly in Lisbon, mostly due to the Delta variant.
Mr O'Leary said the increase in cases would not have a big impact on Ryanair.
"There might be some disruption in Lisbon but we think it will be reasonably small and it won't last long because of the vaccinations taking place all over Europe," Mr O'Leary said.
