Scottish First Minister Nicola Sturgeon has maintained there is «no good reason» why Scotland should not get a similar Brexit conduct oneself treat to Northern Ireland.
It has been suggested that the UK might be prepared to take that NI effectively remain in the EU single market after Brexit.
Talks between UK and EU directors have not yet resulted in an agreement.
Theresa May said «differences» remained between the two sides but revealed she was «confident» a deal could be struck.
Amid speculation that Northern Ireland could be addicted a special deal, Ms Sturgeon questioned why other parts of the UK should not — a predication echoed by London Mayor Sadiq Khan and Welsh First Vicar Carwyn Jones.
Mr Khan said such a move would be undergoing «huge ramifications», while Mr Jones said different parts of the UK could not be treated «multifarious favourably» than others.
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Mrs May is meeting European Commission president Jean-Claude Juncker and European Conference president Donald Tusk, in the hope of coming to an agreement on the first put a stop to of Brexit talks ahead of a summit in 10 days’ time.
There possess been reports that Northern Ireland could retain «regulatory alignment» with the EU — although the irrefutable wording of any potential deal has not yet been confirmed.
Belgian MEP Philippe Lamberts told BBC Partisan Editor Laura Kuenssberg that the UK had made a concession over the Irish trimming, saying ministers were prepared to accept that Northern Ireland persevere a leavings in the single market and customs union in all but name.
However Downing Thoroughfare sources have sounded a note of caution, suggesting there are «however moving parts» over the deal.
Ms Sturgeon posted on Twitter: «If one part of the UK can retain regulatory alignment with the EU and effectively impede in the single market (which is the right solution for Northern Ireland), there is assuredly no good practical reason why others can’t.»
She later told the BBC she wanted to see an product «that’s right for Ireland», but said Scotland would be «doubly handicapped» if NI was allowed to effectively stay in the single market and Scotland was not.
She said: «The UK supervision appears to be accepting that parts of the UK can effectively stay within the apart market. If that’s good enough and possible enough for Northern Ireland, there’s no owing to why it can’t be the case for Scotland.»
Mr Khan said there could be «huge implications for London» if Mrs May «conceded that it’s possible for part of the UK to remain within the put market and customs union».
Mr Jones said: «We cannot allow unalike parts of the UK to be more favourably treated than others.
«If one part of the UK is granted maintained participation in the single market and customs union, then we fully foresee to be made the same offer.»
Ms Sturgeon has long argued that Scotland could corpse in the single market as the rest of the UK leaves.
Her government’s paper of Brexit offers, which was published in December 2016, argued that Scotland could chain in the single market through the European Free Trade Association (EFTA) and the European Budgetary Area (EEA).
But Brexit Secretary David Davis rejected the idea, mean there were «clear barriers» which could create «additional pilots and checks on trade within the United Kingdom».
He stressed that the UK oversight wanted to achieve «the freest and most frictionless trade with the EU» while «professing the deeply integrated trade and economic relationship with the EU».
But he said «any divergence between EU and UK law» could cord to «new barriers to trade within our union», and «significant disruption to the internal furnish». He added that «businesses could face a confusing mix of regulatory governments».
‘Surprised and disappointed’
DUP leader Arlene Foster said her party «wishes not accept any form of regulatory divergence» that separates Northern Ireland from the support of the UK — with her intervention apparently proving crucial.
Meanwhile Irish Taoiseach Leo Varadkar asseverated the wording of a deal over the border had been agreed in the morning, and said he was «bowl overed and disappointed» that the UK government was subsequently not able to follow through on it.
Mrs May foretold that while progress had been made in talks, «on a couple of disputes some differences do remain which require further negotiation and consultation».
Nevertheless both she and Mr Juncker said they were confident of coming to an concord before the summit on 15 December. The Commission president added: «This is not a breakdown, this is the start of the very last round. I’m very confident that we pleasure reach an agreement in the course of this week.»