Military EOD experts have been weighing up options overnight after a suspected Nazi WW2 bomb was discovered on a building site in Southway.
Plymouth Plus understands that the device is believed to be a German WW2 SC250 bomb, according to independent explosive ordnance disposal experts who have examined images of the item.
The bomb is understood to weigh around 250kg and was found at a building site near Flamborough Road and Clittaford Road on Wednesday afternoon.
Around 1,260 homes are being evacuated after the cordon was extended to 400 metres last night on the advice of military bomb disposal specialists.

EOD teams are due to attend a briefing this morning, where a plan is expected to be agreed on for the best way to deal with the device.
The discovery has sparked a major response with Devon and Cornwall Police, Plymouth City Council, the Royal Navy and partner agencies working through the night.
Residents inside the expanded cordon have been told to leave their homes while the specialist assessment continues.

The council has advised people affected to make arrangements to stay with friends or family where possible, with residents currently being told to prepare for up to two nights away.
Anyone who cannot make alternative arrangements has been told to go to Southway Youth and Community Centre in Hendwell Close, where an evacuation centre has been set up.

The centre remained open overnight, with council staff on site to provide support and assistance.
Residents attending the evacuation centre are allowed to bring pets, although dogs must be kept on leads and other animals should be kept in suitable carriers or containers.
People leaving their homes have been advised to take essential items with them, including medication, medical equipment, phone chargers, power packs, important documents, clothes, baby supplies and anything needed for pets.
Road closures remain in place around the affected area, with disruption around Flamborough Road, Clittaford Road, Southway Drive and nearby streets.
Public transport has also been affected, with Plymouth Citybus services diverted away from the area while the cordon remains in place.
Oakwood Primary School and Little Acorns Pre-School are closed today because both are within the 400 metre safety cordon.
Beechwood Primary School has also been advised not to open as a precaution because it is close to the affected area.
The council said the decision was taken to avoid potential disruption during the school day if the cordon needs to be expanded following further assessment by military bomb disposal experts.
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