Theresa May could trigger Brexit within weeks to avoid resentful EU leaders becoming “vicious” in the exit talks, the Irish Premier has claimed.

Enda Kenny said the timetable set down by Ms May – to invoke the Article 50 notice by the end of March – could be derailed by a growing backlash in the rest of the EU.

Speaking before a conference in Dublin on the impact of Brexit on Ireland, the Taoiseach said: “That doesn't mean it mightn't be triggered in December - or January, or February.”

“The other side of this argument may well get quite vicious after a while, because there are those around the European table who take a very poor view of the fact that Britain decided to leave.

“That argument, I think, will be fought very toughly, in a really difficult negotiating sense.”

The refusal of EU leaders to allow membership of the single market unless Britain accepted continued freedom of movement for EU citizens was the critical issue, he said.

Labour seized on the comments to claim they showed the Government’s refusal to move beyond “empty sound bites” on Brexit was backfiring.

Dave Anderson MP, the Shadow Northern Ireland Secretary, said: “Labour has been pressing the Government to spell out their plan, but it is clear they don’t have one.

“It is time we had some real answers and some clarity, so we can see what the Government’s intentions are. That is why it is so vital that Parliament has to get a grip over this process.”

But the Prime Minister’s spokesman insisted that Ms May remained committed to the timetable of invoking Article 50 by the end of next March.

Asked about the suggestion that other EU leaders were turning “vicious”, he added: “We have been very clear that we want to have constructive dialogue with all the member states, a mature debate.”

Mr Kenny was speaking at the All-Island Civic Dialogue, a specially convened forum of politicians, business leaders, community representatives and others from both sides of the border.

He also said Europe had to decide for itself where it wants to be in the years ahead, rather than become “obsessed with what the UK might or might not get”.

Britain's decision to leave the EU was the most significant economic and social challenge to hit Ireland over the last half a century, he added.

The Taoiseach also said he agreed with Ms May that the "benefits of the Common Travel Area" between both countries should be preserved.

The deal, which dates back to the 1920s, secures freedom to travel between Britain and Ireland.

The Republic of Ireland is one of 27 countries that the EU will be negotiating on behalf of, but it is the only member with a land border with the UK.