Manchester United boss Jose Mourinho does not think he would be allowed to make a political statement on the touchline like Manchester City counterpart Pep Guardiola.
Guardiola has recently worn a yellow ribbon – a symbol of protest against the imprisonment of pro-independence politicians in the Spanish region of Catalonia.
He dedicated City’s Champions League win over Napoli last month to the campaigners.
Mourinho said: “If the rules allow us to do that, he is a free citizen. My doubt is if the rules allow any political message on the pitch.
“I don’t think I would be allowed to.”
Guardiola and Mourinho, who meet in the Manchester derby at Old Trafford on Sunday, have been rivals since the former was Barcelona boss and the latter was at Real Madrid between 2010 and 2012.
If City win Sunday’s game it will be their 14th league victory in a row – a record in a single Premier League season.
Guardiola, who was born in the Catalan region, has worn the ribbons to show his support for eight government members jailed for their part in an independence referendum the Spanish government ruled was illegal on 1 October.
Speaking last month, he said: “We cannot ignore that these politicians or activists, who haven’t hurt anyone, are in prison for asking to vote.
“Many things have happened but it’s all because we wanted to vote, because we wanted a legal referendum.”
In 2015, Uefa fined Barcelona £21,250 after their fans unfurled pro-independence banners at the Champions League final in Berlin.
Eighteen years earlier, European football’s governing body fined Liverpool striker Robbie Fowler £900 for revealing a shirt showing support for sacked dockworkers in the city.
Uefa changed its regulations before this season so only offensive messages are now considered illicit.
Last year, the Football Associations of England, Scotland, Wales and Northern Ireland were fined by Fifa for displaying poppies during World Cup qualifiers.