Sinkhole appears in woodland popular with walkers

Mark Sweeting, who found the sinkhole, said he threw a stone in and it "took a while" to hit the bottom

A sinkhole has been discovered by a dog walker in woodland just a few metres from a public footpath.

Mark Sweeting, 53, was out with his daughter in Debdon Wood near Rothbury, Northumberland, on Sunday when he came across the hole, which he estimated to be about 66ft (20m) deep.

He assumed it was part of old mineworks and contacted Forestry England, which manages the land.

Its team, working with the Coal Authority, has now capped the sinkhole and fenced it off.

Mark Sweeting, who found the sinkhole, said he was worried a dog or a child could stumble into it

Mr Sweeting said he and his daughter were following a little track about 20m (66ft) off the main bridleway when he spotted the hole.

"It was perfectly cylindrical, so my first thought [was that] it was a mine shaft or something like that, but then I just thought how dangerous it was and that a dog could easily just go down there, or even a child," he said.

He reported it to the Forestry England on Monday, and working with the Coal Authority, which is responsible for Britain's former mining legacy, it sent a team up to make the site safe.

"I was really impressed by how quickly they got it sorted," Mr Sweeting said.

"It's great to think nobody is going to get hurt there now."

The sinkhole, which is more than a metre across, has now been capped, with warning signs asking people to keep away

In a statement, the Coal Authority said it was "working closely" with partners to investigate what had happened and urged people to report coal mine hazards.

“If this incident was caused by historical coal mine workings, we will design a permanent solution and carry out repair works as soon as we can," it said.

The Coal Authority added it dealt with such incidents "regularly", with 770 mining hazards and subsidence claims investigated last year and10,476 mine entry inspections carried out.