The Tánaiste says the UK government hasn't yet put forward any 'credible' alternative to the Irish backstop.
Simon Coveney's comments come as Boris Johnson has promised a new renewed effort to secure a deal with the EU before the Brexit deadline of October 31st.
The UK's negotiators will now meet their EU counterparts twice a week for the whole of September.
Mr Johnson - who's insisted the backstop must be dropped in any deal - said it's time for both sides to "step up the tempo".
It follows a backlash in the UK over the prime minister's decision to suspend Parliament next month, effectively limiting MPs' chances of preventing a no-deal scenario.
With only weeks to go until Brexit, EU leaders have so far indicated they've heard to no workable alternative to the current backstop:
In Warsaw today for a good meeting w/ PM @MorawieckiM & Minister Konrad Szymanski. The EU is waiting for legally operative solutions from the UK that are compatible w/ the Withdrawal Agreement. pic.twitter.com/YfpIiYH25L
— Michel Barnier (@MichelBarnier) August 29, 2019
Today, Minister Coveney said the EU will be happy to hear any alternatives to the backstop - but a different approach could only be seriously considered if it 'holds up to scrutiny'.
Speaking in Helsinki, he argued: "Michel Barnier is there as the chief negotiator of the EU... he has a team that is ready to go, and we all want to get a deal.
"But at the moment nothing credible has come from the British government in the context of an alternative to the backstop."
He stressed any suggestion that the backstop can be removed and deal with in future negotiations is "not going to fly".