Another £153,000 for the birds

Ken Livingstone has been forced to allocate extra public money - believed to be £153,000 - after the original firm working on Thomas Schutte's Hotel For The Birds went bust.

The German artist's installation was meant to have been unveiled in April, replacing Marc Quinn's marble statue Alison Lapper Pregnant. The delays mean it will now not be ready until next month at the earliest.

Further difficulties have emerged with the decision to construct Hotel For The Birds in glass rather than coloured Perspex, as initially planned.

Schutte, 53, hopes the artwork, modelled on a 24-storey hotel, will poke fun at "obscene" architects who seek to dominate public spaces with faceless, imposing designs - and will also provide a home for the few pigeons that have survived the Mayor's Trafalgar Square bird-feeding ban.

Documents submitted to the London Assembly reveal that the Greater London Authority has now signed a £269,406 contract with German firm Seele for the "engineering, fabricat ion and installation" of Schutte's piece.

The work was chosen, with the Quinn statue, by a panel of experts in 2004 after a major consultation on what to place on the fourth plinth, regarded as Britain's most significant public art space.

Mr Livingstone told the Assembly: "I have approved the use of additional funds for the fabrication of Thomas Schutte's artwork for the fourth plinth due to the insolvency of the company contracted by the artist."

He revealed his cultural team expected to spend more than £600,000 this financial year and a £153,000 "shortfall for the fourth plinth" would be met by transferring funds from a separate budget for running Trafalgar Square and Parliament Square.

As a result of the delay, Alison Lapper Pregnant has now occupied the fourth plinth for more than two years instead of 18 months.

One insider said: "It was always known that Schutte's piece was technically challenging. It's a feat of engineering. We have always thought it didn't matter if Alison stayed up a bit longer."

A spokeswoman for the Arts Council, which spent £160,000 mainly on the public consultation for the original fourth plinth programme, said: "The final piece is going to be made of glass, so that it lasts longer and copes with the wear-and-tear better. That is the key reason why the costs have gone up."

The fourth plinth was designed by Sir Charles Barry and built in 1841 with the intention of accommodating a figure on horseback - probably King William III - but funding could not be found to complete the project.

The plinth has remained vacant for most of its history. Andrea Schlieker, curator for the Fourth Plinth Sculpture Commission, said Hotel For The Birds was chosen because of its use of colour and light.

She said at the time of the piece's selection from a shortlist of six: "Multi-layered, mysterious and promising to sparkle like a brightly coloured jewel, Schutte's utopian architectural vision will have a powerful impact on Trafalgar Square."

Thomas Spitzer, Seele's London-based director, said he had been banned from speaking to the press about Hotel For The Birds. The Mayor's of fice declined to answer the Standard's queries.