Up to 95% of the pier was destroyed as emergency services struggled to get the blaze under control in the early hours.
Hastings Borough Council said the pier was in a "very dangerous state" and advised people to "stay well away".
Two men, aged 18 and 19 and from St Leonards, were arrested on suspicion of arson and remain in custody.
Campaigners fighting to save the derelict pier have vowed not to give up hope that what remains of it may still be salvaged.
Earlier this year, the council agreed to buy the pier with a compulsory purchase order and hand it to the Hastings Pier and White Rock Trust.
Members of the trust have been in meetings with the council and emergency services to discuss carrying out a structural survey.
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