The Medical Director of North East Doctor on Call said that a number of measures to deal with increased demand were made over the Christmas period, but even with those measures in place, demand far exceeded ability to provide services.
Co Monaghan GP Illona Duffy said on two occasions (New Year's Eve and 2 January) there were no available appointments until 1am.
She said this was the first time this had happened and created an unsafe service which forced them to make the decision to stop taking calls, which pushed patients towards emergency departments.
Dr Duffy warned that we have not yet reached the peak of the flu season and that things will get worse over the next few weeks.
She said that the hospital problems are causing a backlog into general practice and some people are being discharged too early, which means they are having to return to hospitals or require more intensive care at homes or in nursing homes.
Dr Duffy told RTÉ's Today with Sean O'Rourke that the free GP care for under sixes has had a massive impact on GP services and the Health Service Executive was warned of this before it was brought in.
She said that while it was a great service to provide, there is a crisis in general practice and not enough GPs to deliver the care.