The English Football Association has called the fan disturbances in Porto an "embarrassment" to the England team.
The side's preparations for the Nations League semi-final with Holland in Guimaraes have been overshadowed by clashes with police in nearby Porto.
Eyewitnesses said some fans started hurling bottles, prompting Portuguese families watching the hosts' match against Switzerland in a fan zone to flee with their crying children as chants of 'England 'til I die' filled the air.
An FA spokesperson said: "The FA strongly condemns the scenes witnessed in Porto overnight.
"Anyone responsible for these disturbances cannot be seen as true England supporters and are not welcome in football. They are an embarrassment to the team and the thousands of well-behaved fans who follow England in the right way."
Just last week the FA launched a video called 'Don't Be That Idiot', highlighting the embarrassment unacceptable behaviour can cause.
That call appears to have fallen on deaf ears and also led to condemnation from deputy chief constable Mark Roberts, National Police Chiefs' Council football policing lead.
"This is the second evening in a row where disorder has occurred in Porto," he said on Wednesday.
"Last night there were issues outside a bar, where bottles were thrown and minor damage was caused.
"It is completely unacceptable. The behaviour we are witnessing is incredibly disappointing and again I would point fans towards the recent video from The FA - 'Don't be that idiot'.
"The behaviour of a small number of the England fans out here continues to tarnish the reputation of the genuine fans who are simply trying to enjoy the football."