A giant sculpture of Aardman Animations' character Gromit, which was decorated by actress Joanna Lumley, has been vandalised just hours after going on display in Bristol.
The 5ft (1.5m) high statue is one of 80 situated at key landmarks in the city as part of a public arts trail to raise money for charity.
Celebrities and designers have decorated the sculptures, with Lumley's covered in lines of hand-written poetry.
The fibreglass model, called Poetry In Motion, was placed on Bristol's College Green last Friday.
But within hours, the tail was ripped off by vandals, leaving a hole in the sculpture.
Over the weekend, a second Gromit sculpture, Carosello by Italian artist Giuliano Carapia, which was placed at Welsh Back in Bristol, was also attacked.
Both models have been sent for repairs and it is hoped they will be rejoin the trail "as soon as possible".
In a statement, Gromit Unleashed said: "We're very sorry to say that, over the weekend, two of our Gromit Unleashed sculptures, Poetry In Motion and Carosello, were damaged.
"They have been sent off for repair and we intend to get both of them back as soon as possible to join the other Gromits on the trail.
"We are dismayed that anyone would want to damage any of these sculptures, which have been created to raise money to treat sick children in hospital and to provide something for everyone in Bristol to enjoy.
"We have reported both incidents to the police, who are currently studying CCTV footage from both sites to try and identify the perpetrators.
"We were elated by the public reaction to the launch on Friday and would like to thank people in Bristol for the tremendous support and enthusiasm they've already shown for this project."
On Friday, Wallace & Gromit creator Nick Park drove a steam train laden with Gromit sculptures along Bristol's historic harbour to mark the start of Gromit Unleashed.
The public arts trail, which will last for 10 weeks, is raising money for the Bristol Children's Hospital charity Wallace & Gromit's Grand Appeal.
Sir Paul Smith, Sir Quentin Blake, Jools Holland, Cath Kidston, Harry Hill and One Direction member Zayn Malik have also decorated Gromit sculptures for the trail.
In October, the Gromit sculptures, which have been sponsored by local businesses, will be sold at auction to the highest bidder to raise funds to support an expansion of the hospital.
Avon and Somerset Police, who received reports of the damage at 3pm on Sunday, are investigating.
Neighbourhood Sergeant Stephen Bell said: "It's hard to understand why anyone would want to damage these colourful characters which are helping to raise money for Bristol Children's Hospital.
"I'd ask anyone who can help us find those responsible to call us on 101. You could also ring the independent charity Crimestoppers on 0800 555 111. They never ask your name or trace your call."