More than 1,000 homes have been evacuated after a suspected unexploded second world war device was discovered at a building site in Devon.

The device was located in the Southway area of Plymouth at around 14:30 yesterday.

Military bomb disposal experts advised Plymouth City Council to extend a cordon from 200m (650ft) to 400m (1,300ft) to allow its specialist teams to “continue their work safely”.

The council is supplying large quantities of sand to help ensure the device remains stable while specialist operations continue.

Devon and Cornwall Police expected around 1,200 homes to be evacuated and have asked people to leave for up to two days. Schools within the cordon have also been advised to close.

In a statement, Plymouth City Council said: “We appreciate this is a worrying situation and we thank residents for their patience and cooperation. Plymouth City Council continues to work closely with the police, the Royal Navy and partner agencies to ensure the safety and wellbeing of everyone affected. Further updates will be provided as soon as they are available.”

The name of the contractor responsible for the building site has not been disclosed.

There were more than 50 bombing attacks on Plymouth between 1941 and 1944 during the second world war. Official records estimate that at least 2,820 bombs fell on the city, with about 10% failing to detonate.