Calls are being made for urgent action to be taken to ensure the Grade I-listed Sheerness Boat Store does not deteriorate.

The Naval Dockyards Society is urging Swale council to ensure site owners Peel Ports carry out a condition survey, remedial works and arrange regular inspections to make sure it is not deteriorating.

The boat store is the world's oldest surviving example of a multi-storey iron-frame and panel structure following the destruction of the Crystal Palace and the first South Kensington Museum.

Completed in 1860, it was the world's first multi-storey building with an all-metal frame.

The structure was made rigid through pioneering use of portal bracing, which is a form of support that covers a large area without too many columns.

It left a big mark on the architectural world, and the technique was subsequently adopted by early skyscrapers in Chicago and became universally used in modern steel-framed buildings.

The site is currently not in use.

The Naval Dockyards Society said Swale council had: "accomplished sterling work in completing the Sheerness: Royal Dockyard and Bluetown Conservation Area Character Appraisal and Management Strategy (March 2011).

“However, the fact the boat store has been on the At Risk Register for 20 years is an indictment of the level of care by Peel Ports.

“Its condition (Historic England South East At Risk Register 2018) is 'very bad'.”

The society added Peel Ports had launched its Sheerness Port Master Plan - a 20-year strategy for growth - in November 2014 and aimed to create a Heritage Quarter and improve integration with the local area, but "made no commitment to refurbish listed buildings at risk".

A council spokesman said the authority was very concerned about the building’s condition and "possible further deterioration".

He added that its officers had been on site last month discussing safeguarding the structure.

A Peel Ports spokesman said: “Following a recent inspection of the condition of the listed assets of which some have been refurbished or repaired we are working closely with Swale council and Historic England to implement a phased plan of repair to the Boat Store.

“Peel Ports remains committed to investing in safeguarding our assets across the group.”

The society has now asked Swale council what deadlines it is giving Peel Ports to carry out works to remedy the boat store situation, and is urging the authority to ensure it carries out a condition survey, remedial works to make sure the building is weather-proof and secure, and arrange regular inspections by Historic England to make sure it is not deteriorating.

It said: “The society's comments regarding the boat store and associated structures are intended to be constructive within the overall framework of seeking to conserve naval heritage.”