The fire which destroyed part of Eastbourne Pier may have been started deliberately, detectives have said.
Initially it was suspected that an electrical fault could have sparked Wednesday's blaze on the 144-year-old attraction.
Sussex Police said they are now treating the fire as "suspicious" as information points to it being "started by someone, either deliberately or accidentally".
Up to 80 firefighters tackled the inferno on the Grade II*-listed Victorian attraction, which left the dome-shaped amusement arcade near the entrance a scorched shell.
Detective Inspector Mark O'Brien, of Sussex Police, said: "As a result of our investigation we have received information to suggest that the fire may have been started by someone, either deliberately or accidentally, and our investigation is now focusing on that line of enquiry.
"A temporary scaffold platform has been erected adjacent to where the fire is thought to have broken out in order to enable scenes of crime officers and fire investigators safe access to the area."
The development from police came after Prime Minister David Cameron and Chancellor George Osborne saw first-hand the damage wrought on the pier.
Their visit to the coast coincided with the announcement by Downing Street that up to £2 million will be given to help Eastbourne's tourism industry recover from the loss of the attraction.
Mr Cameron and Mr Osborne visited the 1,000ft (305m) pier and met firefighters and RNLI lifeboat crews who helped save two-thirds of the attraction.
They also spoke to community leaders as the pier's closure comes at the height of the all-important summer tourist season for the resort.
Mr Cameron said: "I know that the loss of one of Eastbourne's most prominent and well-loved landmarks will have hit the town hard and I am determined to do all I can to help local businesses recover."
After the visit, the Prime Minister said the pier was insured and its owners - Cuerden Leisure - were committed to rebuilding it.
Mr Cameron added: "Obviously it's a scene of some devastation, with the burnt and twisted metal, but what strikes you really very early on is really how much of the pier has been saved by the incredible bravery, professionalism and hard work of the firefighters and also the RNLI and the police who did a brilliant job in getting to the scene so quickly.
"Now what we need to do is make sure that Eastbourne doesn't suffer from what has happened and that's why we are giving £2 million to the council so they can help the traders, help the businesses and make sure that everyone hears the message loud and clear that Eastbourne is open for business."
Mr Osborne said: "We will work with Eastbourne as a matter of urgency to ensure that the funding is provided without delay so people can start enjoying the pier again."
Meanwhile, coastal communities minister Penny Mordaunt named 10 coastal towns which will receive £8.5 million.
The money will be used to boost tourism, regenerate historic sites and provide new flood defences, Downing Street said.
Mr Cameron and Mr Osborne also announced an extra £3 million to encourage growth and create jobs in coastal towns.
Eastbourne MP Stephen Lloyd has said the pier could reopen next year as two-thirds of it was untouched by flames and the structure appeared "pretty sound".
He said: "It's still very much still standing, and I'm very hopeful and confident that it will be reopening next year and be back in business."
The Liberal Democrat MP has called on the community to rally round the pier's stricken traders amid fears that some had no insurance.
The fire also put paid to the plans of couple Helen Brook and Stuart Pearce who were due to get married on the pier in three weeks' time.
The couple were due to wed on a section still intact, but their dreams for their big day have now left them "shell-shocked" because of the blaze.
No-one was trapped as the pier was evacuated quickly at around 3pm.
East Sussex has been cursed by the devastation of some of its beloved piers in recent times.
In 2003, the 148-year-old West Pier in Brighton was reduced to a mangled mass of metal by two major blazes within two months.
And in Eastbourne's neighbouring town of Hastings, the Grade II-listed pier was almost destroyed in a fire in 2010 following years of neglect by its then-Panama-registered owner.
Efforts are now well under way to restoring Hastings Pier after more than £13 million was secured mainly though the Heritage Lottery Fund.