The National Trust for Scotland has come under attack from its trade union, Prospect, for allegedly failing to consult its stakeholders over recent cost-cutting measures aimed at ensuring the continuing financial sustainability of the charity.

The board of trustees came under criticism in a recent report by Prospect for neglecting to disclose its plans to make 90 redundancies and close 11 of its historic properties - including Kellie Castle, Haddo House and the David Livingstone Centre - until too late in the day.

The union's attack has been compounded by criticism over funding for the Robert Burns Birthplace Museum project, which is putting the charity under pressure to find a £3.8m shortfall during an already financially difficult period.

However, chief executive Kate Mavor has defended the decisions, saying: "While it's fair to say that, like many other organisations, we are facing challenges at the moment, we are making good progress in strengthening our finances and we anticipate that we will be in surplus by the end of this year.

"Our finances are reviewed regularly by both our internal and external auditors and we are regulated by the Office of the Scotland's Charity Regulator which has not highlighted any concerns.

"We are acting now to ensure our finances remain stable for the long term. These decisions are never easy, but it is our belief that they are essential."

Conservative culture spokesman Ted Brocklebank has also alleviated concerns that the trust is spiralling into debt by proposing that each of the 300,000 members make a one-off contribution of £20 to put an end to the current deficit crisis.