Devon and Cornwall Police declared a major incident on Tuesday and evacuated properties within 200 metres of the bomb.

One hundred armed forces personnel were on the scene to assist the evacuation, and the Ministry of Defence said bomb disposal teams were helping to make the device safe.

In an update on Thursday morning, Plymouth council said the cordon has been extended to 309 metres, affecting 1,219 properties and an estimated 3,250 people.

It comes after residents were asked on Wednesday evening to make sure they have essential items such as clothes, medicines and baby items for "at least a 36-hour period".

'Very scary moment'

A local Keyham mechanic from Wayne's Mobile Mechanic Ltd told Sky News that he was evacuated from his family home on Tuesday with his wife and three children.

"We were evacuated on Tuesday around lunchtime and it's been a very scary moment for myself, my wife and three children," he said.

"We are currently staying with our granddaughter Demi and grandson Grayson Blu."

When asked what the reaction of the community has been, he said: "It's unbelievable and very scary as we live yards from the scene."

He said he was not sure when the family will be let back into their home, but has heard it might possibly be the weekend.

Officials started knocking on doors from 8am this morning and a free shuttle bus was put on to pick residents up every 15 minutes, the council said.

People have also been encouraged to make arrangements to stay with friends and family over the next couple of days.

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The council said those being evacuated will be taken to Plymouth's Life Centre which has been set up as an emergency rest centre with tea and coffee, blankets, towels and toothbrushes, a creche and faith room available.

Those who have already been evacuated will be able to return to their homes to collect "urgent, essential items only" including medication or a pet, the council said.

Officers were first called to a property on St Michael Avenue in Keyham after a man said he found the device while digging out the foundations for an extension.

The Royal Navy's Explosive Ordnance Disposal (EOD) team is among those at the scene.

Earlier on Thursday, images showed tonnes of sand being delivered to the area, which a police source told Plymouth Live, will be used to build a sand wall around the unexploded bomb.

Among those affected was Teresa Cork, who had travelled from her home in the Prince Rock area to Keyham to rescue her son and daughter-in-law's cat.

"It's eerie. I went over to feed the cat yesterday and it is very eerie, and also quiet," she said.

"Today it is a bit more scary because there is a lot more people - a lot more official people. There are sandbags everywhere and a bit more reality."

'My husband hasn't been out the house for six years'

Carol Wheeler told Sky News on Wednesday that she was concerned about the cordon being widened.

She said: "I find that difficult because I've got a disabled husband and at the minute there's no plan in action of how we're going to get him out because he hasn't been out the house for six years.

"It will be difficult. It takes four people to lift him down the stairs, plus he's got loads of electronic equipment and he's got motor neurone disease.

"He's non-verbal, and I've had to have a day off work as well. I can't move the car, I can't go out and do any shopping but they say the cordon is going to be expanded a bit more."

Bomb 'found about a week ago'

Speaking to Plymouth Live, the man who called police over the device said he actually found it "about a week ago".

"I hit something with a spade but we weren't sure what it was at first," he said.

"Since then we've had so much rain, the bank collapsed, then there was more rain on Friday and it's been revealed more and more...

"By this point my wife said we really should just call the police and alert them. I took photos and sent them off and a sergeant in Exeter rang me... saying he needed to send them off to EOD.

"Five minutes later there's a knock on the door and police officers asking to have a look. The next minute they're suggesting a cordon."

Plymouth saw more than 50 bombing attacks during the Second World War, and in 2011 an explosive device was unearthed by a workman at a building in Notte Street, near the city's Hoe.

The device was made safe before it was moved to the seabed off Plymouth Sound, with an exclusion zone around it.