A charity which collapsed last month with the loss of 600 jobs was experiencing financial problems at least two years ago after it was confirmed managers were failing to pass on workers' pension contributions.

Management at child care provider One Plus deducted pension contributions from staff salaries but failed to hand over the money to fund managers.

As the state of the charity's finances begins to unravel, the union which represented more than one-third of staff has also confirmed that thousands of pounds of subs were also taken off wages for over a year yet not paid.

But the Transport and General Workers Union "did not make a song and dance" about the money as there were already concerns about the financial viability of the charity well over a year ago.

Since Glasgow-based One Plus went into liquidation former senior staff have contacted The Herald with evidence of the financial mismanagement which led to it folding. It is reckoned the financial black hole could be as much as £9m.

It has emerged that as far back as two years ago management were combating on-going funding crises and were making up financial shortfalls by using monies designated for other purposes. Administrators at Strathclyde Pension Fund were made aware of the situation when contributions were being made in "dribs and drabs" and raised their concerns with One Plus.

According to Glasgow City Council it is the one and only time the Pension Fund has had to step in and warn any of its 200 members over their failure to make contributions.

Fund sources described the situation as indicative of "incompetency within One Plus". The source added that when the fund managers demanded to know why payments were not being made "the money flowed in".

Last night a spokesman for the fund said: "We were concerned in 2005 that payments to the fund on behalf of One Plus employees were not progressing as normal. We contacted contributors to make them aware of the situation.

"This action led to payments being made to the fund and, as such, all contributions due by the management of One Plus have been made in full."

John Findlay, who founded One Plus and was the chief executive until last September, denied the accusations of mismanagement.

He said: "Payments were late but as far as I was aware all contributions were up to date by the time I left. The payments were late because of cash flow difficulties."

KPMG, which was appointed liquidator, is currently working through the One Plus accounts to establish the full extent of the debt and what contributed to the collapse.

It has already emerged the Inland Revenue is owed several millions in unpaid National Insurance contributions, while other creditors include HBoS, which is again owed several millions.