Britain should threaten the “weak” Republic of Ireland with new border controls in order to get its way over Brexit, Ukip has said.

Gerard Batten, the party Brexit spokesperson, said Ireland was “a tiny country that relies on UK for its existence” and that it amounted to “the weakest kid in the playground sucking up to the EU bullies”.

The MEP said the UK had been “threatened” by the Republic over the issue of the Irish border after Brexit and that Britain should “respond in like manner”.

“We should advise, we are free to revoke common travel area,” he said, adding that the Republic was “nothing but a subservient client state to the EU”.

Irish prime minister Leo Varadkar said earlier this month that Ireland needed “written” assurances from the UK that there would be no return to a hard border between the north and the Republic after Brexit – a position both sides have said they support.

The Taoiseach hinted that if no such written promise was made Ireland would not deem sufficient progress to have been made in negotiations to move to trade talks at the upcoming December European Council summit.

If “sufficient progress”, as defined by the EU, is not agreed in December, the next opportunity to start trade and transition talks will be in March – throwing the Brexit talks timetable into even more disarray and dramatically increasing the likelihood of a ‘no deal’.

After an outcry on social media Mr Batten doubled down and said it was “amazing how upset some people have got because I have suggested Ireland threatening to derail [a] Brexit agreement could invoke a response”.

Ireland is currently part of the Common Travel Area with the United Kingdom, which has existed since 1923 and means travellers do not require a passport to travel between the UK, Ireland, Isle of Man and channel islands.

Both are also currently members of the EU customs union, meaning goods moved between the two countries do not need customs checks – but Theresa May has committed the UK to leaving it as part of her plans for a hard Brexit. 

The EU, Ireland, and UK are wrestling with how to avoid a hard border between the Republic of Ireland and Northern Ireland – as required by the Good Friday agreement – while also ensuring the EU still has an external customs border. 

The European Parliament and European Commission have suggested customs checks could be moved to ports on the Irish Sea, effectively keeping NI in the customs union and putting a customs between two parts of the United Kingdom.

The DUP, on which the Government relies on to have a majority in the House of Commons, has however ruled out any such plan, as has David Davis the Brexit Secretary. 

The issue was one of two which, along with the financial settlement, European Council president Donald Tusk has said requires “much more progress” before December’s European Council summit.

In a statement sent to The Independent after the initial publication of this article, Ukip head of delegation Ray Finch MEP said the party’s Brexit spokesperson did not speak for the party on the issue.

“Mr Batten’s late night tweets do not reflect UKIP policy or sentiment,” he said.

“We wish to maintain free trade and free movement between the North and South of Ireland, full stop.”

Instead, Mr Finch said that the best way of solving the border issue was for Ireland to leave the EU too.

“Outside the EU, Ireland would once again operate as a sovereign self-determining State with the opportunity for global Free trade, and an independent foreign policy without membership of an EU army,” he said. 

“The best way to avoid the European Commission imposing a hard border is to create an equal partnership of independent states outside EU.”