The Taoiseach has described Boris Johnson's reopening plan as "a free for all".
Micheál Martin said the Government is very concerned about the plans to fully ease restrictions in England.
From July 19th the vast majority of the COVID-19 restrictions there will be lifted in what's being dubbed "freedom day".
However, Taoiseach Micheál Martin believes that's not the way Ireland should go.
He said: "I do think in respect of the UK... I am concerned about the free for all that seems to be developing within the UK.
"That does raise issues for us as a people and as a country, because we're next-door neighbours - what happens in the UK can spill over very quickly.
"Our public health advice would be that's not the way to go."
Meanwhile, the head of the HSE warns the Delta variant could put pressure on the testing system.
The more transmissible variant has led to a sharp rise in cases of COVID-19 in the UK, with the incidence rate in Ireland also rising.
Tánaiste Leo Varadkar says cases are likely to rise over the coming weeks, although the impact is likely to be "totally different" to previous waves.
Paul Reid says there is concern around the impact of the variant here.
He said: "We do know most likely cases will rise, and challenge testing and tracing systems.
"It's certainly not completely clear at this stage the full impact on hospitalisations... but we are monitoring what's happening very closely across the UK, and other European Union countries that have a prominence of the variant."
It comes as the HSE says 300,000 people are set to be vaccinated this week.