A restaurant chain has apologised after sparking outrage when it cut down an oak tree in London that was believed to be up to 500 years old.

Described by British conservation charity the Woodland Trust as “one of London’s largest and most significant ancient trees,” the huge oak was located outside a branch of Toby Carvery, a popular restaurant chain known for its roast dinners, in Whitewebbs Park in the borough of Enfield.

The tree’s remains, surrounded by its severed branches, were discovered by council workers on April 3. Enfield Council owns the land the tree was located on, and it is leased to Toby Carvery.

The owner of Toby Carvery, Mitchells & Butlers, said the chain was advised by contractors to cut the tree as it “caused a potential health and safety risk.”

With a girth of 6.1 metres, the tree ranked in the top 100 of London’s 600,000 oak trees for size, according to the Woodland Trust.

“I am outraged that the leaseholder has cut down this beautiful ancient oak tree without seeking any permissions or advice from Enfield Council,” said Ergin Erbil, the leader of Enfield Council, in a statement Wednesday. “We have evidence that this tree was alive and starting to grow new spring leaves when this action was taken.”

He said the council believes the action has “broken the terms of the lease which requires Toby Carvery to maintain and protect the existing landscape.”

“The tree was the oldest one on site and cutting it down seems to be a clear breach of this condition. This tree would have been home to countless wildlife, fungi, and pollinators. This tree is a part of our ecological and cultural heritage,” he added.

The council said it is considering legal action.

According to the council, when experts inspected the oak in December, it was deemed “healthy” and “posed no risk” to the neighbouring carpark and its users. An emergency tree preservation order has been imposed on the base of the stump, the Woodland Trust said.

A spokesperson for Mitchells & Butlers said in a statement to CNN that the felling of the tree was “an important action to protect our employees and guests as well as the wider general public.”

“We took necessary measures to ensure any legal requirements were met,” it added.

Phil Urban, the chain’s CEO, later apologized for “all the anger and upset that this incident has caused.”

“Clearly the felling of a beautiful old tree is a very emotive subject and is not something that any of us would undertake lightly,” said Urban in a letter addressing the incident. “We cannot undo what has been done,” he said, adding: “We need to tighten our protocols.”

Benny Hawksbee, who lives in Enfield and is a member of the Guardians of Whitewebbs group, said in the Woodland Trust statement that people want “answers.”

“The tree belonged to Enfield and to our national heritage. I am devastated,” said Hawksbee.

Jon Stokes, director of trees, science and research at the Tree Council, said in the trust’s statement that ancient oaks can live up to 1,000 years.

Despite the damage, council leader Erbil said the oak “shows clear signs of life,” adding: “We will also do everything we can to help the tree regrow.”

The Metropolitan Police Service told CNN in a statement Thursday that it was treating the felling as a civil matter and has closed its investigation.

This is not the first time that the felling of a tree has sparked outrage in the United Kingdom.