Ian Smith, chief financial officer of Yorkshire Bank's parent company CYBG, said: "We absolutely support getting a sensible deal. We absolutely need a deal because no deal is a disaster.
"Politicians (who support a no-deal Brexit) have other motivations, most of which relate to self interest. The facts and evidence are incontrovertible. No deal would be a substantial economic shock to the UK."
His comments came after Prime Minister Theresa May said that MPs have to choose between backing her plan or “leave with no deal or no Brexit at all”.
Under a no deal scenario, the UK would revert to World Trade Organisation rules.
CYBG's chief executive David Duffy also warned over Brexit uncertainty.
"Clearly Brexit negotiations mean the external political and macroeconomic environment remains inherently uncertain," he said.
"We have planned for a period of uncertainty, but it is impossible to ignore the lower levels of business confidence, especially for SMEs, while the final specific outcome of negotiations remains unclear."
Mr Smith said that Brexit has "certainly had an impact" on the housing market.
"Customers are less willing to trade up and buy new properties in the current market. It's all related to consumer confidence. On the business side, our customers are delaying hiring and investment decisions," he said.
The pair were speaking as CYBG announced it had gone into the red after an extra £150m charge for the mis-selling of payment protection insurance (PPI).
The group, which has drawn up plans to rebrand itself as Virgin Money after the £1.7bn takeover of the Virgin brand last month, reported a £164m pre-tax loss in the year to September 30, down from a £268m profit in 2017.
The group was hit by £396m of legacy conduct costs, the bulk of which were linked to PPI claims.
Many banks have seen an increase in complaints volumes following a Financial Conduct Authority advertising campaign featuring Arnold Schwarzenegger to encourage people to come forward before an August 2019 deadline for final claims.
However, Mr Smith said the TV campaign had had "next to no effect".
"Claims came down during the period the advertising was on," he said.
"We are much more sensitive about how much business is being driven by claims companies.
"Early next year CMCs (claims management companies) will be brought within the scope of FCA regulations, which is a pretty daunting prospect for them."
CYBG said that, while weekly complaint volumes have been falling since the end of July, it considers it prudent to take a further £150m increase in provisions as it estimates 83,000 future claims.
"Our base case is things will get better," said Mr Smith.
On an underlying basis, CYBG's pre-tax profit rose 13 per cent to £331m and net interest income rose 1 per cent to £851m.
The tie-up with Virgin Money is expected to result in annual cost savings of around £120m by the end of September 2021.
With more than six million customers, the bank will also hold £70bn in customer loans and around £58bn in mortgages.
The plan is to switch all retail customers over to the virgin Money brand name.
"We expect it to play out over a couple of years. Customers haven't noticed a difference so far," said Mr Smith.
"We've had feedback from customers saying we'd prefer not to lose the brand, but we've also had feedback that the customer experience trumps the history and emotional attachment.
"We are hugely committed to Yorkshire and the North of England."
CYBG is doing research with SMEs to decide whether to switch business customers to the Virgin name.
"We can decide not to rebrand if we choose. At some point next year we'll make a decision, but we haven't set a date," said Mr Smith.
CYBG has said that 1,500 jobs will go across the business over three years.
In terms of branches, it has promised to ensure that customers can access a branch within a reasonable distance.