UK ministers do not have a "full estimate" of how much the collapse of construction services company Carillion will cost the taxpayer, Liz Truss, the Chief Secretary to the Treasury, has said.

Although Ms Truss argued that it would be "completely wrong" to speculate on the cost, she admitted it would be a "significant amount of money".

She told ITV’s Peston on Sunday: “At the moment we don't have a full estimate; we heard about the collapse last week, we've been working to make sure public services keep going, that's of course our most important priority.

"There's a lot of investigatory work to do in terms of what the directors knew and when they knew it but also making sure that we can move those contracts on, either to organisations within the public sector or to other private sector organisations.

"It's right that that's our priority - making sure things work - but of course we will be doing a sort of post review of understanding what the total costs are," she explained.

Ms Truss was later challenged on whether she was being "economical with the truth" about the cost of the collapse to taxpayers and said: "There's a difference between the cost that the administrator finds and what the impact will be on public spending and public services.

"What I'm talking about is the cost to the taxpayer, which there will be, but we don't know until we find out exactly which bits will be run by other parts of the private sector, which bits will be run by the individual Government departments where we can find savings and efficiencies, which I am constantly looking for."

Her comments came as Theresa May warned that huge fines would be imposed on irresponsible company bosses, who "line their own pockets".

The Prime Minister is expected to outline plans in the coming weeks ways to crack down on "abuse" of the system by business chiefs following the Carillion collapse.

Meanwhile, Ms Truss was also asked about comments by Carolyn Fairburn, the head of the CBI, who said remaining in a customs union with Brussels was the best option for British business.

The Treasury Minister said: "It's very important that we don't just listen to the big players, we also listen to those who want to enter the market, the new businesses starting up, the exciting new disruptors who might have different ideas about the way of doing things.

"The whole point about the customs union is if we remained in the customs union, we can't run an independent trade policy, we can't get the best possible deal on a trade deal with America or the Far East where a lot of those new opportunities are emerging from," she added.