Eight women from separate households met at a local beauty spot to walk their dogs, a councillor has said.
The octet were stopped by police at Pontsticill on Sunday and were reminded that the coronavirus restrictions prevent meeting others outdoors for exercise.
Acting council leader for Merthyr Tydfil County Borough Council, Lisa Mytton said the women were spoken to by police carrying out an exercise in the area following reports that people were driving there for exercise.
Cllr Mytton said: "Well extremely grateful to our SWP Merthyr officers but extremely disappointed with members of the public.
"SWP have just done an exercise in Pontsticill and towards Dolygaer they have not only stopped and cautioned several people in vehicles from Aberdare, Ebbw Vale etc, but also a local group of young girls, eight in totall all mixed households met up walking their dogs together. They are issuing penalties!
"We are in lockdown, the ignorance will not be tolerated, this is a serious situation our NHS Covid staff are on their knees.
"More people have this deadly virus and more of out friends, neighbours, family are dying!
"If people do not listen lockdown will continue sadly. The message is stay home! When you do exercise you must only do that with members of your household!"
Deputy Leader Lisa Mytton is currently acting head of the council after council leader Kevin O'Neill was suspended for seven months for breaching code of conduct.
A spokesman for South Wales Police confirmed that officers were in the area on Sunday.
He said officers spoke to a number of people about the coronavirus guidelines - but no penalties were issued.
