The UK's Brexit Department is facing further scrutiny after the government refused to immediately disclose how much the ministry has spent on private consultants, it emerged on Friday 30 June.
The development comes after senior Labour MP Jon Trickett quizzed Brexit Secretary David Davis over the issue with a written question in the House of Commons.
Conservative MP Steve Baker, the newly appointed Brexit minister, told Trickett that the department had used the service of a "number" of consultancy firms to help with the ministry's planning and establishment after the Leave vote at the EU referendum in 2016.
"A small number of individuals are also on secondment from the consultancy firms and external organisations," Baker said. "The department will make further use of external support and recruitment as appropriate to ensure it has the right expertise available."
He added: "The total expenditure on professional services and consultancy in the financial year 2016/17 will be published in the annual report and accounts. Specific contracts awarded over £10,000 and items of expenditure over £25,000 will be reported in due course."
Trickett, who has held numerous posts in Jeremy Corbyn's top team, said the government had done nothing to answer his question, which "raises serious issues" about the nature of Whitehall.
"There has been much speculation on conflicts of interest from the over-reliance on huge consultancy firms. Civil service staff should be guided by an ethos of public service, not by the profit motive, interests of clients or the position of their shareholders," he told IBTimes UK.
"On top of this, there has been much criticism of the revolving door between these huge multi-nationals and government, where the British establishment feathers its own nest."
Trickett added: "I will not abandon this – if taxpayers' money is being spent, it should be accountable to them. They should know which businesses have the ear of one of the most important Secretaries of State.
"If David Davis can't answer a simple question in Parliament, the British Public will be interested in knowing if he shares information elsewhere. I will try to find out exactly how much is being spent, on whom, and if those staff are then given access to the heart of Whitehall via the secondment system."
The comments come as the two-year-long divorce talks between the UK and EU continue. Prime Minister Theresa May has promised to split from the bloc's single-market and seek a bespoke customs deal so that Britain can broker its own trade arrangements with non-EU nations.
But her cabinet seem to be split over a post-Brexit transition period, with Chancellor Philip Hammond suggesting such a period could last up to four years, while Davis said the UK would split from the EU's single-market and customs union in 2019.
Corbyn, meanwhile, has sacked a number of shadow cabinet ministers after they defied the Labour whip and backed a vote on keeping the UK in the single-market and customs union in the Commons on Thursday evening.
The amendment to the Queen's Speech, which was tabled by Labour's Chuka Umunna, won the support of 101 MPs, including 49 Labour MPs.