A trade union leading the fight against austerity is under fire over plans to spend £2.2million transforming its plush headquarters in one of Edinburgh's best streets.

The Educational Institute for Scotland (EIS) - the main union for teachers - is using its budget to create a better working environment for its members and staff.

The EIS has blamed poverty and budget cuts for attainment figures which continue to show pupils from deprived backgrounds getting comparatively poor results.

General Secretary Larry Flanagan spoke at a recent anti-austerity protest in Glasgow and wrote recently: "Austerity has an impact on our schools. The link between poverty and educational attainment is clear so it should come as no surprise that an increase in poverty in our society appears to be reflected in attainment in our schools."

However, the EIS is now facing questions about the use of its own resources.

According to the union's latest accounts, 54,580 members paid around £5.5m in contributions and subscriptions in 2013/14.

Around £2.6m was paid in staff remuneration and expenses.

The accounts also flagged up a huge sum for overhauling the union's four-storey block in Moray Place, based in the Capital's New Town.

The grand A-listed building, marked by polished ashlar sandstone and timber sash and case windows, was bought by the EIS in 1948 for £10,000 and is now valued at £3.5million.

The union last year concluded a refurb contract which started in October and is expected to be completed this year.

The main work is to be carried out by GHI Contracts Ltd for £1,523,401 - minus VAT - but the total project will cost £2,250,000.

This includes furniture, equipment, consultants' fees and irrecoverable VAT.

According to a planning application lodged with the city council this year, the EIS wanted to change the use of the basement at number 48 from offices into overnight accommodation.

The variation would "provide the EIS with a source of continued revenue", by creating a flat that could be "rented or used by Board members as required".

However, an EIS spokesman said the plan now was simply to rent out the new flat.

Another application, lodged last year and granted, showed that "various alterations" were planned for all floors.

On the ground floor, the EIS wants to erect a new full height glazed partition, put an opening through masonry wall, remove existing toilets, and box in a fireplace.

Similar adjustments are being made on the other floors. Last year's application aimed to deliver a "cohesive design look" and "consistently high quality feel throughout".

The prized accommodation is part of the union's £4.1m property portfolio.

As well as the building in Moray Place, the EIS has 6 Clairmont Gardens in Glasgow - worth £600,000 - and 34 West George in the city, valued at £95,000.

According to the accounts, Flanagan receives a remuneration package worth around £117,064.

This includes £89,791 in salary, £10,094 in employers' national insurance, and a £27,275 pension contribution.

The main grade salary scale for unpromoted teachers is between £21,867 and £34,887 a year.

Tory MSP Alex Johnstone said: "This is the height of hypocrisy from Scotland's biggest teaching union. It's all very well banging the drum about poverty and austerity - but perhaps their members would be surprised to learn they're actually spending millions on sprucing up their own offices in Edinburgh.

"Member contributions should be going towards helping workers fight problems at work - not refurbishing their plush offices in one of the capital's most desirable areas."

EIS President Pat Flanagan said: "The work that has been undertaken has included structural work, specialist asbestos removal, essential upgrades to facilities such as electrics and plumbing, as well as redecoration of all buildings and the installation of new fixtures and fittings in offices and meeting rooms.

"In addition to housing EIS staff, the HQ buildings are used to host a wide range of member events and committee meetings. As part of the refurbishment process, new training facilities are being created which will be utilised to support the development and training of EIS members, representatives and branch secretaries from across the country.

"While the sums of money that have been allocated are clearly significant, the quantity of work that was required and the fact that three listed buildings are being refurbished made this level of investment necessary in order to protect the buildings and ensure a safe and secure working environment for members and staff."