The bishop of a diocese that straddles the border between Northern Ireland and the Irish Republic has warned Boris Johnson to "tread carefully" with his Brexit plans.

The Rt Rev John McDowell, the Bishop of Clogher, wrote in the Daily Telegraph that Brexit and the question of the Irish backstop appeared "very worryingly" to be "escalating towards a crisis". 

Regardless of what the Government does, he said that the decision would be of "historical magnitude" as he cautioned the Prime Minister to "give deep pause before allowing a no-deal Brexit". 

"For those of us old enough to have lived through [the] longest civil conflict in post-War Europe, the very word 'escalation' is resonant with overtones of lived horror and real tragedy," he said.

"As such, it is reassuring that those in power on both sides have repeated their desire to find answers to the brexit/border conundrum problems that protect what has been achieved here since 1998."

In a speech on Saturday, Johnson called the backstop "anti-democratic" and said it must be ditched if a deal is to be reached with the EU. 

"If we get rid of the backstop, whole and entire, then we are making a lot of progress," the Prime Minister said.

Bishop McDowell urged the Prime Minister not to be "irresponsible or careless", nor to commit the country "to a course of action in which the consequences were so opaque as to be incalculable".

"It would, therefore, be both logically and morally correct for a prime minister to give deep pause before allowing a no-deal brexit," he said. 

"The border and the problems which it poses for any form of brexit are not only technical or technological issues. Nor are they simply issues to do with trade or security matters.

"Expressed in the starkest terms, the Border is the background against which all political and much cultural life in Northern Ireland (and in a more limited way in the Republic of Ireland) is worked out.

"Some people like the border and others do not, but positively or negatively, consciously or unconsciously, it is pivotal to how politicians and people here assess almost all policy alternatives." 

He continued: "The ground on which people build and grow in the border region feels particularly fragile today. It is almost possible to feel the heat of the past burning the soles of our feet.

"So, please, in your consideration of the future of this place: tread carefully. And with deep and genuine concern I would ask you to be very conscious of the legacy your government will leave."