A community group is reeling after a historic lido it was hoping to return to past glory was vandalised during an illegal rave.

The Cleveland Pools site in Bath is the country's oldest open-air swimming pool and was recently put on the market by Bath and North East Somerset Council, despite pleas by a charitable trust set up to bring it back to public use.

Now vandals have broken into the lido and scrawled dozens of graffiti tags all over the Grade-II listed changing rooms and cottage, which date from when the baths were built in 1815.

The attack has come as a real blow to members of the 1,500 members of Cleveland Pools Trust, who were hoping to open up the landmark to the public for a series of heritage open days taking place throughout the city next weekend.

Group spokesman Janice Dreisbach was horrified by the damage and said the council had been slow to clean it up. She said: "As the site is on the open market, we no longer have the keys to it so have to depend on them to clean it up.

"One of our trustees, Ann Dunlop, went to the baths on August 18 for a meeting and was horrified by the state of the buildings and reported them to the council.

"But, according to the property agents, they are still in a disgusting state and we have no idea if we are even going to be allowed to open them up for public view next weekend."

Ms Dreisbach said the open days were the only chance members of the public had to see the baths now the site was on the market.

A council spokesman said: "Work has started on clearing the graffiti but hasn't been completed because of the bad weather. It will be removed, weather permitting, before the heritage event on September 12, 13 and 14.

"The council is committed to improving the public realm and graffiti removal plays an important part in this."

Cleveland Pools Trust had wanted to be given a lease at peppercorn rent to breathe new life into the site and open it up for public swimming for the first time in 20 years. But to acquire the property it will now have to bid against other would-be buyers.

The trust plans to put in a nominal bid for the site and is likely to be backed by businessman Trevor Osborne.

The baths in Hampton Row have not been in regular use since 1978, were reopened as a trout farm in the early 1990s and put up for sale in 2004, although the trust then persuaded the council to halt the process while it developed a business case for its own plans.

City firm Brooks has now been given the job of marketing the complex.

It is thought there has been a great deal of interest but no firm offers as yet.

Estimates of the money needed to bring the baths back into use vary from £700,000 to £1.5 million, and the trust would be looking to raise money from lottery fund sources.

Its business plan said the facility could generate income of up to £150,000 a year and could operate at a profit if it used volunteers.