Speaking in Brussels, Micheál Martin said that the current situation is very serious.
A sub cabinet meeting is due to take place tomorrow, between the Taoiseach, Tánaiste, and Ministers for Health, Transport, Public Expenditure, and Finance to discuss Nphet's recommendation that the entire country move to Level 5 restrictions for six weeks.
Tánaiste Leo Varadkar has said the Government will make a decision "in due course" on the recommendation to introduce level five restrictions.
Mr Varadkar said he "wasn't surprised" by the advice, with levels of the virus rising rapidly, but said Cabinet will not meet today to act on the recommendation.
He told reporters: "The co-ordination group will meet and after that Government will consider NPHET's advice, taking into account the public health implications, but also other implications too, around the impact on society, on the economy, on livelihoods, on mental health.
"We'll make a decision in due course but there are no plans for a Cabinet meeting today."
NPHET has written to Health Minister Stephen Donnelly to recommend introducing the strict lockdown measures for a period of six weeks.
It is the second time the health advisory group has called for level five measures, with the Government refusing to do so when first asked two weeks ago.
The National Public Health Emergency Team (NPHET) has recommended that the entire country moves to Level 5.
Minister for Health Stephen Donnelly was advised of the recommendation in a letter last night.
NPHET are recommending the highest level of restrictions for a period of six weeks.
In Level 5, people would be restricted to moving within 5km of their homes, pubs and restaurants would operate on a takeaway basis only and public gatherings would largely be banned.
The issue is to be discussed at a meeting between Government officials and Chief Medical Officer Dr Tony Holohan today but, as of now, there are no plans for a Cabinet meeting today.
Taoiseach Micheál Martin is currently in Brussels and is not due back in the country until later today.
Prof. Gerry Killeen, AXA Research Chair in Applied Pathogen Ecology at the School of Biological, Earth and Environmental Sciences at University College Cork said that a move to Level 5 would be the “right thing to do”.
He said that while six-weeks at Level 5 would not be enough to take Ireland to an end-point in terms of Covid-19, that this time should be used to have a conversation of what path to take next - whether to crush the curve or live with the virus.
Professor Killeen said that if we continue on the current path, the number of cases of Covid-19 being reported may “at best” level out, but with action, Cork could be back to where it was in mid-June by Christmas.
This morning the HSE’s chief clinical officer and NPHET member Dr Colm Henry warned that the widespread uncontrolled community transmission of Covid-19 represented “the greatest threat to our healthcare services.”
If nothing was done that would lead to hospitalisations and intensive care admissions that no healthcare system could deal with, he told RTÉ radio’s Today with Claire Byrne show.
Dr Henry also warned that it would be difficult to keep schools open if the rate of transmission continued to rise.
Dr Henry pointed out that on Thursday night there were 235 cases of Covid-19 confirmed in the country’s hospitals, compared to eight at the beginning of August.
He said the two-week incidence rate of the virus had now surpassed 200, compared to just three per 100,000 at the end of July.
“We are now seeing the impact on other countries that are ahead of us in their experience of this second wave. On hospitalisation, on intensive care units and tragically on deaths,” Dr Henry said.
“There is no reason we would not expect our projections to be any different from what is happening in mainland Europe.”