Engineers have carried out a test closure of two giant steel floodgates as part of a £2.5 million revamp of harbour sea defences.

The gates, part of the Environment Agency's new Queenborough barrier on the Isle of Sheppey, can close in just two minutes compared to a 30-minute wait before.

The barrier, which is opened and closed by hydraulic rams, is at the mouth of Queenborough Creek and protects 311 properties from flooding caused by surge tides.

The original barrier was built in the early 1980s.

Accumulated silt from around the old floodgates had to be removed by a dredger in June and taken away by road before a low-level cofferdam could be installed to allow engineers access to the site.

A new silt management system to prevent the build-up of waste has been added to ensure the gates will always be able to work.

Gordon Henderson, MP for Sittingbourne and Sheppey, was among the guests invited to see the test closure on Friday.

He said: “It is a very impressive structure. I am very grateful to the Environment Agency for its hard work and money spent on this valuable asset at Queenborough."

He added: "I am impressed with the way the structure operates and the backup systems to ensure its resilience.”

The Environment Agency has also built a control room overlooking the channel to improve the safety of boats when the barrier is operated.

Bat boxes have also been installed outside the control room.

Julie Foley, the Environment Agency's area director, said: “It is great news we have modernised the Queenborough Creek barrier which provides better flood protection to hundreds of homes and businesses on Sheppey."

But she added: "We still want people to be aware of their flood risk. They can find this out by signing up to our free flood warning system on the www.gov.uk website."

The barrier was built by contractors Balfour Beatty and CH2M and completed ahead of schedule.

Land around the creek is earmarked for regeneration. New homes are planned. Former industrial premises are being demolished. Earlier plans for the area included a design for a marina.