Hundreds of residents from properties surrounding the site where a Second World War German bomb was detonated remain unable to return to their homes.

The device, believed to be a 1,000kg “Hermann” bomb used by the Nazis, was discovered on a building site on private land to the west of the University of Exeter campus in Exeter on Friday.

Initially, a 100-metre cordon was erected, but this was extended to 400 metres on Saturday at the request of the Royal Navy bomb disposal team.

Residents at about 2,600 properties around Glenthorne Road, including 1,400 university students, were evacuated.

The device was destroyed in a controlled explosion on Saturday night with the blast being heard from several miles away.

The original cordon has reduced but several hundred residents remain away from their homes, including 500 students.

Exeter City Council said no decision had yet been made on when the cordon would be lifted.

“The council thanks residents for their patience and will publish updates as soon as they become available,” a spokesman said.

“The council is asking those residents who live within the reduced cordon who haven’t been put up in hotels to contact the council.

“The University of Exeter has confirmed that 1,400 students were evacuated from their accommodation and 900 have returned today.

“Around 500 remain displaced until it is safe for them to return.”

Dr Todd Gray, a historian at the University of Exeter, said the bomb was most likely to have been dropped by the Luftwaffe in April or May 1942 during a series of attacks known as the “Baedeker” raids, which were carried out on several historic cities.

“In total there were 19 air raids on the city but those in the spring of 1942 caused extraordinary damage and a high loss of life,” he said.

“The blitz of Exeter was the single most destructive event in the city’s history since at least the attack by the Vikings in 1003.

“In total nearly 300 Exonians lost their lives and 1,734 buildings were destroyed. Another 18,849 properties were damaged.

“Thousands of incendiary bombs and 80 to 100 high-explosive bombs were dropped on Exeter in the final raid. Around 40 high explosive bombs did not detonate.

“Although the Baedeker bombings were intended to crush morale, the Luftwaffe did not merely attack Exeter just for its beauty – strategic sites were targeted including the railway, which lies near the site of the unexploded bomb.”