Theresa May's plans for trade post-Brexit may have been backed by her Cabinet, but they have not been agreed by the EU, Scotland's constitutional relations minister has warned.

Michael Russell welcomed the agreement the Prime Minister had secured from her ministers as "further movement towards a soft Brexit".

But he cautioned that the proposals were only the UK's position - "an opening shot rather than a closing shot" - and criticised May's government for not consulting enough with Scottish ministers.

He spoke to STV News the day after the Cabinet signed up to plans which could keep the UK closely tied to Brussels.

After a day of intensive discussions at Chequers, May managed to secure the agreement of her top ministerial team to proposals setting out the country's future relationship with the European Union.

The plans, which still have to be assessed by the 27 other nations of the EU, would result in the creation of a UK-EU free trade area for goods, with a "common rulebook".

Meanwhile a new "facilitated customs arrangement" would remove the need for checks and controls by treating the UK and EU as if they were a "combined customs territory".

Scottish Tory leader Ruth Davidson welcomed May's prospectus as "a pragmatic set of proposals" that would deliver for Scotland.

She also slammed the SNP, saying it had "used the Brexit referendum as a pretext for pulling our country apart".

First Minister Nicola Sturgeon earlier responded to the agreement on Twitter by declaring it "game on" for campaigners hoping to keep the UK in the single market and the customs union after Brexit.

Her Brexit minister echoed the sentiment, describing full membership of the European single market and customs union the "only tenable solution".

Russell told STV News: "This is a further movement towards a soft Brexit, so to that extent I welcome it, but it's not far enough and it's certainly not moved fast enough.

"The UK will have to continue to move - I don't think they realise that, that this is an opening shot rather than a closing shot.

"I think there are a number of difficulties with it too, that will make negotiation hard.

"But I also think Scotland needs to be consulted on some of the details - that hasn't happened.

"We haven't seen the full paper that's to be issued later this week; some of the areas in which they're talking about are devolved areas, which we are responsible for."

The minister continued: "As a final note of caution, this is what the UK wants, this is not an agreement with the EU.

"As recognition of that, the stepping-up of preparations for a no-deal are very worrying indeed because whatever happens this is going to be bad.

"Leaving the EU is not going to be good for the economy, whatever scenario, but a no-deal would be a disaster."

On Thursday, the Scottish Government submitted its own "realistic and workable" Brexit proposals to UK ministers ahead of the talks at Chequers

They include a plan to retain membership of the European single market and remain part of the customs union.

Russell said: "The only tenable solution short of staying in the EU, which is the right thing to do and we know that now the vote was essentially based on a false prospectus from a whole range of people.

"But the only possible alternative is full membership of the single market and the customs union.

"That is on offer, a sort of Norway option. That is what we've recommended.

"We put a major paper to the UK Government on Thursday that showed how this could be done.

"We're taking the mainstream, practical and sensible solution; the Tory government seems to spend more time fighting amongst itself than thinking its way forward."

Leading Brexiteer Jacob Rees-Mogg has already warned he will have to wait to see "have the red lines been turned pink", as he claimed the proposals could be worse than a no-deal Brexit.

Speaking on BBC Radio 4, he said: "As with eggs, an egg that is very softly boiled isn't boiled at all. A very soft Brexit means that we haven't left, we are simply a rule-taker. That is not something that this country voted for, it is not what the Prime Minister promised."

However, Scottish Conservative leader Ruth Davidson said the newly outlined Brexit plan would deliver for Scotland in three key areas.

She said: "The proposals agreed at Chequers are welcome and provide clarity as the UK government moves to the next round of negotiations with the EU.

"For Scotland, they deliver in three key areas - providing Scottish business with frictionless access to the EU market; withdrawing the Scottish fishing industry from the hated Common Fisheries Policy and, by ensuring no border in the Irish Sea, bolstering Scotland's biggest and most important market, the UK internal market."

Davidson added: "There are further commitments to upholding shared high standards in goods, agriculture and the environment, which are to be welcomed."

She accused Nicola Sturgeon's party of having "used the Brexit referendum as a pretext for pulling our country apart", adding: "Now is the time to put differences aside.

"The UK is leaving the EU. On the table is a pragmatic set of proposals that go a long way to addressing the concerns of those worried about the economic impacts of a hard Brexit.

"An admission from the SNP that such fears have been largely addressed would help reassure Scotland's business, agri-foods and fishing communities."

But Scottish Labour leader Richard Leonard hit out at the Conservatives.

He said: "This sticking plaster solution, which has taken two years to reach, simply underlines how shambolic the Tories' handling of Brexit has been.

"Previous allegedly unanimous positions in Theresa May's government have quickly fallen apart - and there is no reason to think this will be any different."