The Government is in thrall to "Brexit nutters" on its backbenches, an SNP MP has said, as the Commons prepares to debate the customs union.

Later on Thursday MPs will debate a non-binding backbench motion supported by a number of select committee chairs which calls on ministers to secure an "effective customs union" between the UK and the EU after Brexit.

Speaking at Business questions before the debate, SNP Commons leader Pete Wishart said: "Is the Government going to come out and play today in today's customs union debate, or is it going to continue to contemptuously refuse to vote in non-Government business?

"Because can I say to the Leader of the House, there is no running away from this and this will have to be confronted by this Government, and it looks like they haven't got a majority.

"All of the business community are saying they want 'a' or 'the' customs union, but yet they're in thrall to Brexit nutters in the backbench here, who still hold some sort of sway over this Government.

"So can the Leader of the House confirm that if the Government is defeated, the will of the House will be respected?"

Shadow Treasury minister Anneliese Dodds said the Government's earlier statement on stamp duty land tax appeared to have been scheduled so it could "pat itself on the back while reducing the amount of time spent on the issue of customs union with the EU".

She said: "I appreciate that issue may be controversial albeit only for the Government - every other actor seems to feel that some kind of customs union is a good idea - but that shouldn't prevent democracy from running its course on that issue."

Ripping up existing trade deals could be "deeply damaging" to jobs and communities, the chairwoman of the Home Affairs Committee has warned.

Labour's Yvette Cooper, opening a backbench business debate on customs and borders, said time was running out for Parliament to "help shape the negotiations" and to hear from the Government about what it is going to do.

"The Government rightly says it wants frictionless borders, no extra burdens on business to improve trade, no hard border in Northern Ireland and including no infrastructure at the Northern Ireland border," she told the Commons.

"But there is still no clarity about what that actually means at our borders."

She said Britain does more than £230 billion of export trade with European countries every year, as she warned that many manufacturing jobs depend on frictionless trade.

Ms Cooper added: "At a time when it could take very many years to negotiate new trade arrangements, the idea that we would rip up our existing ones in the meantime would be deeply damaging to many of our jobs and communities."

Tory former minister Anna Soubry said it seemed "perverse" that Britain wanted to "put up a whole load of barriers" to stop access to the "best free trade area" in the world.

Ms Soubry said: "Does she (Ms Cooper) agree with me that it seems rather perverse that at a time when we want to increase free trade, we're going to put up a whole load of barriers to stop access in that best free trade area that is existing in the world?"

Ms Cooper agreed, saying: "Where we have good free trading arrangements in place actually we should cherish them because the honest truth is it's getting harder to negotiate new trade deals - the politics of trade deals have become more complex as communities across different individual countries become more worried about both the losers and the winners of big changes to trade arrangements."

Conservative former minister John Redwood asked Ms Cooper to explain how "we have such a smooth-running, fast growing and very large trade with the rest of the world on WTO terms where we have to pay EU tariffs and we're not allowed to negotiate them down all the time we're a member of the customs union".

Ms Cooper said she thought Mr Redwood was "making the point that our trade was growing within the current arrangements with the rest of the world - that seems to be a good thing and suggests that perhaps therefore we can carry on increasing our international trade and our global trade even within customs union arrangements".