A fire service boss said he is "astonished" by large groups gathering for barbecues on the moors amid the coronavirus outbreak.
Greater Manchester Fire and Rescue Service said people were meeting to cook food despite a ban on moorland barbecues after huge fires in 2018.
It also flouts the government's instructions on social distancing.
Fire station manager Dave Swallow said their actions were "dangerous" and urged people to stick to the rules.
"It's just amazing how many people don't seem to be getting the importance of the social distancing guidelines," said Mr Swallow.
"It's astonishing when you to throw in the fact that people are taking disposable barbecues out there and cooking."
Despite Government advice to stay at home today we've had reports of lots of people having barbecues on the moorlands and this is very dangerous.— Greater Manchester Fire & Rescue Service (@manchesterfire) March 25, 2020
It pose a huge risk of fire, is a risk to the environment and ties up our firefighters who may be needed for more serious incidents.
Oldham Council approved a public space protection order (PSPO) in September 2019 after moorlands in Greater Manchester were devastated by wild fires.
A large blaze near Saddleworth Moor took three weeks to be put out in the summer of 2018.
In April 2019, up to 50 firefighters were needed to tackle a blaze that broke out on Saddleworth Moor overnight.
In recent days, the fire service has already been called to a number of small grass fires and West Yorkshire Fire and Rescue Service had to tackle a blaze at Deer Hill Reservoir in Marsden.
Mr Swallow has urged the public to "observe the restrictions the government has put in place" and to adhere to the PSPO.
"It's been so busy [on the moors] that you will struggle to adhere to the social distance guidance," he added.