NICOLA Sturgeon’s group of SNP MPs has a critical role in the fight to secure a soft Brexit, according to a key Brussels politician.

MEP Philippe Lamberts said the First Minister had substantial political leverage at Westminster which could be applied in the days ahead of the crunch EU summit next week.

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Lamberts said the SNP are in a strong position, with 35 MPs compared to the DUP with just 10. He said: “Maybe the SNP could negotiate supporting the Government on the Brexit deal and get something from it. I would go to May and say if you negotiate staying in the single market and customs union we might support you.”

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Lamberts was, however, reluctant to say if the First Minister could demand a Section 30 order for a second independence referendum, in return for SNP support on a soft Brexit deal. “I don’t want to comment on that,” he said.

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He was less confident of the First Minister being able to negotiate a special Brexit status for Scotland even if Northern Ireland secures one as it was not put into the negotiating position by the UK Government – despite Scottish Government demands.

Lamberts is co-chair of the Greens/European Free Alliance, a group of MEPs. He is also a member of the European Parliament’s Brexit Steering Group – chaired by fellow Belgium MEP Guy Verhofstadt. The group updates members of the European Parliament on the EU/UK negotiations and will advise them ahead of any vote that may take place to approve the terms of the UK’s exit from the bloc.

The SNP oppose the UK leaving the EU, but as a compromise have consistently called for the UK as a whole to remain in the single market and customs union – an option which would keep the UK in full alignment with EU rules under the same arrangement as Norway and prevent a hard border between the Irish Republic and Northern Ireland.

There has been speculation the UK could agree to regulatory checks at Irish Sea ports as part of a backstop deal in the event of no other solution to the border situation. But Arlene Foster, the DUP leader, made clear last week she would not support any increase in regulatory checks across the Irish Sea as a means to break the deadlock over the Irish border. Stressing the party’s unwillingness to give ground on the issue, she said: “The red line is blood red, it is very red.” The lack of agreement from the DUP to a deal means May needs to get support from elsewhere.

Membership of the single market and customs union would mean the UK would have to accept free movement of people and pay into the EU’s budget, though it would not participate in the Common Fisheries Policy.

Supporters of a soft Brexit say it would cause the least economic damage to the UK, though opponents such as ex foreign secretary Boris Johnson, say it would restrict the UK’s ability to negotiate its own trade deals. Brexiteers also oppose the arrangement as it would mean the UK would have to accept the EU rules and standards without having a say in creating them.

Lamberts wants the UK to accept single market and customs union membership which he says is the only feasible way of maintaining a frictionless border in Ireland. He hopes the UK will change its mind on Brexit and if it does leave will seek to join again. Speaking in a debate last week in Strasbourg, he told his fellow MEPs said: “To those – especially in the United Kingdom – who blame the EU27 for lack of flexibility, I will say this: We cannot be held responsible for resolving intractable contradictions in the British position.

“Indeed, it is this Government’s choice to interpret the referendum as a decision to leave both the single market and the customs union. It is also its choice to refuse any form of special status for Northern Ireland, and it was its free choice to be party to the Good Friday Agreement that brought peace to Ireland. These three constraints are incompatible with one another, and resolving this British contradiction can in no way justify the dilution of the single market, one of the Union’s key pillars.”

A spokesman for the First Minister said that short of remaining in the EU, the Scottish Government continues to push for continued membership of the single market and customs union, which is around eight times the size of the UK market alone.

He added that the First Minister had been absolutely consistent on that, and will remain so – as she has said, the closer we get to a no-deal outcome, the more that the common sense option of continued single market and customs union membership comes back into play.