Arsonists are thought to be behind a fire that destroyed the dinosaur sculpture on Southsea Common.
Firefighters were called at 2.40am today after reports it was ablaze.
The 53ft steel and hard polyester ultrasaurus model, which arrived in Portsmouth in August, was totally destroyed.
An investigation will now be carried out into the cause.
Robin Dellow, watch manager of Southsea fire station, said it was impossible for the dinosaur to spontaneously combust.
He added: 'We are treating this fire as "cause doubtful", which means it was not an accident.
'We cannot say for definite that it was arson but we are not ruling it out.
'There is nothing combustible around the dinosaur, and although there was a fluorescent light inside the dinosaur it was still there when the fire fighters arrived.
'This shows it was nothing to do with the fire.'
Do you have a picture or video of the dinosaur on fire? E-mail firstname.lastname@example.org
Scott Yule, a firefighter from Southsea, who attended the blaze, added: 'As soon as you came on to the seafront you could see the fire.
'The dinosaur was well alight when we got there and there was a group of university students taking pictures and videos on their phones.
'It was rainy when we got there but not enough to put out the fire, but it was windy which would have helped the fire.
'The dinosaur was completely destroyed, it is unrecognisable.
'You can see the metal frame, but that is all.'
Speaking about the popular dinosaur he added: 'We were surprised when we got the call.
'It is not something that you see on your job sheet every day – a dinosaur alight.
'People here have children that were excited when they heard that the dinosaur was coming, so it was a shame to see such a focal point on the seafront destroyed in a matter of minutes.'
The statue, called Luna Park, was brought to the city by Portsmouth art group aspex, but it is owned by Cardiff's Chapter Gallery.
It was due to leave Southsea on October 10 for Colchester.
It was then supposed to travel to Cardiff, but Portsmouth City had hoped to bring it back permanently when its tour ends in April.
Portsmouth City Council leader Gerald Vernon-Jackson said: 'People enjoyed having the dinosaur here. It was an interesting addition to the seafront.
'Everyone enjoyed it and we were looking at ways to find out if it was possible to keep it here.
'Obviously that isn't going to happen now.
'It was supposed to Colchester next but we did want it to come back.
'How stupid can anybody be? 'This was obviously deliberate – it was raining last night.
'It's incredibly dangerous to set something of that size on fire.'
Hampshire police said they would be investigating the cause of the fire.
PC Jack Oakley, from Portsmouth's Targeted Patrol team, said: 'What we're dealing with currently is an unexplained fire.
'We're looking into the possible causes to establish whether it was accidental or deliberate.
'We've got police and fire experts looking into the possibility of forensics although unfortunately the current bad weather is not helping.
'I understand there were a number of people who witnessed the fire and took footage of it on their mobile phones and I'm hoping they will be able to help my enquiries.
'I'm appealing to anyone who was on Southsea Common at the time and who saw what happen, or anyone with information about the cause of the fire, to get in contact.'
Anyone with information is asked to contact PC Oakley at Southsea police station on 101 or 0845 045 45 45 from outside Hampshire and the Isle of Wight. You can also call the anonymous Crimestoppers charity on 0800 555 111.
SCULPTURE HAD BECOME A POPULAR SIGHT ON THE COMMON
People on Southsea Common this morning spoke of their anger at the destruction of the dinosaur.
The dinosaur had become a popular sight on the Common, with the city council even wanting to keep it here permanently.
Harvey Hamilton, 11, of High Street, Old Portsmouth: 'I think it's really sad they've destroyed it.
'I really liked it.
Daniel Lomen, 26, of Monarch Place, Locks Heath, said: 'The people who did this are complete idiots and they should be made to pay for it.'
Steve Kaye, 45, from the Isle of Wight, added: 'It's disgusting – I loved that dinosaur.
'I thought it was superb. I wanted it to stay here permanently.'
Lindsey Evans, at Colchester's firstsite gallery, which was due to receive the dinosaur, said: 'It's such sad news. We're very unhappy this has happened.'