The longest pleasure pier in the world and a Grade II-listed sculpture are among a city’s heritage assets worth £30m, councillors have heard.

In an annual report to Southend-on-Sea City Council, auditors revalued the landmark pier at £25m and said the 1971 Civic Fountain by William Mitchell was also worth millions.

Conservative councillor Judith MacMahon told the audit and governance committee there was concern assets could be overlooked because their historic value was not known, including other Mitchell sculptures within the council building.

She added his work was worth “astronomical amounts of money” and there was a financial risk to the council if they were undervalued and then damaged.

After being informed there was sometimes difficulty in valuing assets such as statues, Ms McMahon said: “I explored it in comparison to pieces of work that had been purchased in the States and you were talking in millions.

“You’re not talking any less than that.

“A piece of his concrete that was about one foot square sold for £100,000 in an auction, so quite valuable.”

The auditors’ report said the authority’s land and buildings were revalued over a five-year cycle, with the pier subject to a full revaluation since the last report, said the Local Democracy Reporting Service.

Last year, the council committed more than £6m to prevent the pier falling into the sea.