Safety fears have been raised after a large hole appeared next to a busy Cramlington street.
Residents first noted the hole next to the Northburn Sports and Community Centre alongside Crow Hall Lane last December, and have watched with concern as it grew bigger and bigger.
It is believed the cavity is above an old access shaft to a former mine.
Cramlington town councillor Wayne Daley fears the current depression in the ground could eventually crumble, leading to a 70 metre deep hole.
The area has now been cordoned off and Coal Authority engineers have begun work to re-fill the site in a bid to make it structurally sound.
Coun Daley said: “This hole is 70m deep on land right next to over 2,000 houses.
“This is not the first time holes like this have appeared in Cramlington.
“I am concerned that the Coal Authority isn’t proactive enough to identify known risk areas and ensure the safety of these sites by informing local people.
“We need to be vigilant and report any areas of land which appear to have sunk before it gets worse and causes an injury or fatality.”
Town councillor for Cramlington West, Barry Flux, added: “This is clearly a massive concern given the safety issues involved.
“I have asked the Coal Authority what work is being undertaken to ensure that the mine work entrances are safe within the local area.
“I want assurances that the ground is stable so that Cramlington residents can be reassured that our parks, fields and infrastructure are safe from the possibility of massive holes appearing at a moments notice.”
Engineers will drill down to the level of the old mine workings, and then fill the hole.