Construction giant Carillion had just £29 million in cash by the time it went bust, according to its interim chief executive.
Keith Cochrane said the company was in talks with the Government to save it for months and added that it was "regrettable" that discussions to arrange short-term funding had been unsuccessful.
In a High Court document, Cochrane added that Carillion made a "formal request" for support from the Government on December 31, following talks during the final months of 2017.
As recently as Sunday (January 14), directors believed that a "constructive dialogue regarding short-term funding" was under way in order to rescue the company, Cochrane said.
However, while discussions were ongoing, he accused the Royal Bank of Scotland (RBS) of taking "unilateral action which in the company's view undermined the group's efforts to conserve cash."
He said the RBS asked for certain bank payments to be pre-paid, which had a negative impact on the company's liquidity of between £2 million and £20 million.
The Government then denied the company's final request for help which led directors to conclude that it was insolvent.
Firms working for Carillion on private sector contracts will only have Government support until Wednesday, Cabinet Office minister David Lidington said.
Carillion is currently engaged in public sector or public-private partnership contracts worth £1.7 billion, including providing school dinners, cleaning and catering at NHS hospitals, construction work on rail projects such as HS2 and maintaining 50,000 Army base homes for the Ministry of Defence.
The group, which employs around 20,000 British workers, has been struggling under £900 million of debt and a £587 million pension deficit.