"If we take the timetable seriously, and we do, then in October we need to come back with something on paper regarding the EU's position and based on the discussions that took place in Salzburg", a senior European Union official told New Europe, who added that the European Union leaders need to develop a "common understanding" on what a future political declaration will say.
He will then meet Mr Coveney separately.
"If we are to get out of this mess, and get the great British motor back on track, then we need to understand the Irish backstop, and how it is being used to coerce the United Kingdom into becoming a vassal state of Brussels", he added.
News of the move - which is "likely to cause tit-for-tat retaliation by Europe", says The Times - came as Theresa May hinted that she too backs a global system rather than one giving preferential treatment to European Union citizens.
"The government's urgent priority must be to secure a withdrawal agreement".
"I think that the alternative to that will be having no deal".
He stressed that the EU needed to protect its single market from Britain piggybacking on Northern Ireland's special status and to provide a "legally operational" solution - meaning he will resist a political fudge in language or a deal that would push resolution of the Irish problem until after Brexit in March and into negotiations on a future EU-UK trade agreement.
The EU's involves Northern Ireland following EU law on customs and goods, a plan May has said no British prime minister could ever accept.
Diplomats say they are expected to hold a special Brexit summit in Brussels in mid-November.
"We need to challenge the assumptions of both these Irish backstops, or we are heading full throttle for the ditch with a total write-off of Brexit".
Although Gibraltar is not part of the EU customs union, businesses fear regulation of the border could become more rigid following Britain's exit from the EU, with detrimental effects for the thriving economy of the tiny territory.
Both sides have proposed fallback plans, known as backstops, that would kick into place if trade talks fail to settle the question.
"We respect the territorial integrity of the United Kingdom", he said, speaking to journalists at a news conference.
But with large numbers of Tory hard Brexiteers openly rejecting the Chequers plan, Liberal Democrat leader Sir Vince Cable said the scene was set for a second referendum.
Khan said the "sensible thing" would be for the prime minister to call a general election if she did not have support for any Brexit deal.
"This means that our relatives struggle to get visas to come to the UK for family celebrations, restaurants can not employ skilled chefs from overseas, our temples can not bring in priests, and we can not bring people in for business, cultural or sporting as well as the thousands of talented professionals like doctors, teachers and engineers", said Gujarati-origin Priti Patel, former UK Cabinet minister and a prominent pro-Brexit campaigner.
Theresa May will use Tuesday's gathering in Salzburg, Austria, to make a direct pitch to fellow leaders to back her divisive Chequers proposals.