The European Union has accused Britain of “magical thinking” over Brexit and warned it against using the Northern Ireland peace process as a bargaining chip in EU-UK negotiations.

Britain in turn accused the EU of failing to understand the "human cost" of the hard-won Northern Ireland peace process as a furious war of words broke out just days before negotiators meet in Brussels for the third round of Brexit talks.

One senior EU official demanded that Britain make a political commitment “where the UK accepts responsibility for the consequences its decision to leave will have on the island of Ireland.”

“The decision to leave was the UK’s decision, not the decision of Ireland and not the decision of the EU and the UK has to take responsibility for that, “the official said in Brussels.

Britain published a series of position papers before the third round of Brexit negotiations in Brussels next week, including one on how to protect cross-border trade between Ireland and Northern Ireland after Brexit.

Both Britain and the EU agree that customs controls and border checks risk inflaming old tensions but the EU believes that Britain is trying to tie the Irish issue to wider talks about trade.