A £121 million bridge project that was initially held up by an unexploded Second World War bomb has faced further delay – from a vole.

Builders found evidence of the small rodents near the third river crossing that is under construction in Great Yarmouth, Norfolk and work was temporarily halted.

While a “potential burrow” was identified, no voles were found and work was allowed to continue, Norfolk County Council said.

Voles are protected in law, under the Wildlife and Countryside Act 1981, and it is an offence to kill, injure or take them.

It is also an offence to disturb them in a place used for shelter or protection, or to damage, destroy or obstruct access to such a place.

A potential burrow was recently identified in a new area close to where we were working so we took measures to protect it

The infrastructure project, named the Herring Bridge, previously faced delay in February when a 250kg bomb was found.

The device detonated while work to defuse it was ongoing, with locals reporting that they felt buildings shake and that some car windows were broken, but nobody was injured.

Graham Plant, cabinet member for highways, transport and infrastructure, told a Norfolk County Council meeting on Tuesday: “The bridge was obviously held up by a couple of things that went on.

“One is obviously a bomb, and that held things up for at least 10 days because things had to be reinstituted after that.

“And believe it or not we had a visit from a vole, which are more highly protected than bats, and we had to find him a new home before work could continue.

“So unfortunately there’s about two or three weeks it was held back.”

He had been asked when the bridge was due to open, and replied: “I’m reliably informed around about September time the bridge will be open and operating.”

A Norfolk County Council spokesperson said: “We have always been aware of the presence of voles around the site perimeter and have managed our work in accordance with the relevant legislation.

“A potential burrow was recently identified in a new area close to where we were working so we took measures to protect it by creating an exclusion zone and called in ecological experts but no voles were found and no further action was required.”