Newcastle say they will take "appropriate action" against forward Joelinton after he appeared to breach coronavirus rules by getting a haircut.
The Brazilian, 24, posted a photo on Instagram, which has now been deleted, of him having his hair cut by a barber.
All hair salons and barbers in England are currently closed under lockdown regulations.
"We are disappointed by the image shared by Joelinton," said a Newcastle United spokesperson.
"There are clear Covid-19 protocols in place and the club continues to guide and educate its players on their responsibilities.
"The club will be taking appropriate action internally.