A councillor has been called "reckless" for promoting theories on linking coronavirus cases with 5G masts.
Mark Holland said "a so-called virus" was "being used to disguise radiation from 5G masts designed for killing".
The independent Blaenau Gwent councillor linked a spike in cases in Brynmawr with a nearby 5G mast.
Steve Thomas, leader of the council's Labour group, said the posts sent a "dangerous" message after the borough went into local lockdown last week.
The World Health Organization has said there is no evidence of a link between 5G and coronavirus.
Mr Holland, ward councillor for Six Bells, said the Facebook posts were his personal views, not the council's.
He denied being a "conspiracy theorist" and said he stood by his views.
Mr Thomas told the Local Democracy Reporting Service the posts were "deeply, deeply concerning, especially taking into account the huge rise in Blaenau Gwent cases in the past eight days".
"There is a danger that this information can influence people to put themselves and others at risk," he said.
"I cannot believe that a local authority member can be so reckless when the stakes are so high."
All of our elected representatives should be very clear that these are conspiracy theories. Good to see the leader of @BlaenauGwentCBC make clear that he does not endorse this dangerous & irresponsible rubbish. https://t.co/wokA4roRhI— Vaughan Gething MS (@vaughangething) September 28, 2020
Mr Thomas has called on council leader Nigel Daniels, to "take urgent action" over the issue but Mr Holland accused the council's Labour group of politicising the issue and said they were "ignorant to the facts of 5G".
In response, Mr Daniels said: "The social media posts by councillor Holland are his own personal views and they are certainly not shared by myself or other elected members of the Independent group.
"This is an unwelcome distraction at a time when we are focusing our resources on managing the current challenges presented by coronavirus as we aim to keep our communities safe and to slow the spread of the virus."
Blaenau Gwent council chairwoman Amanda Moore said: "I do not associate myself with that in anyway whatsoever."