The head of a European football supporters' group has hit out at UEFA's "terrible" ticketing policy for Champions League and Europa League matches.
Liverpool fans are being charged £73 for a ticket to their Champions League semifinal against Roma next week, after paying £66 for the trip to Porto in the round of 16 -- three times more than home fans.
Football Supporters Europe is set to lobby UEFA to tighten regulations on prices to prevent clubs from increasing prices for visiting fans.
"There is a general perception that if a club is rich, then its fans are rich," Ronan Evain, the chief executive of Football Supporters Europe, told the Daily Telegraph. "There is a belief that if a club has a huge support, then the share of fans who are able to afford expensive tickets is bigger. "As British football is the richest in Europe, the fans of British clubs are regularly targeted. But we also have examples of fans from French and German clubs who have suffered from the same ticketing policy."
UEFA regulations state the price of tickets for visiting teams must not exceed "the price paid for tickets of a comparable category that are sold to supporters of the home team".
Shakhtar Donetsk fans were charged €50 (£43) by Roma for tickets for their round-of-16 tie this season, while Porto charged RB Leipzig fans €50 for their group stage match.
Home fans who are season ticket holders or members at some clubs have received discounted tickets, so pay less than visiting fans when tickets are not on general sale.
"Our argument is that if the clubs know they are going to sell everything in pre-sale, then they are in breach of UEFA regulations," Evain added. "If the whole of the home section has access to the pre-sale prices, then the fans in the away sector are paying higher prices than the fans in the home sector. When 95 per cent of the stadium has a discount, this is not a discount any more.
"If they are not in breach then the regulation is too loose and is allowing too many loopholes. Clubs are getting smarter in the way they approach the Uefa regulations and these kind of terrible ideas are travelling pretty fast in European football."
UEFA ordered Anderlect to partially refund Bayern Munich fans back in February after the Bundesliga club were charged €100 (£87) for tickets.
Manchester United fans were charged €100 for their round-of-16 tie at Sevilla but United subsidised them by increasing the price for visiting supporters attending the second leg at Old Trafford.
A UEFA spokesman said: "Since the pricing strategy regarding ticketing is under the responsibility of the home club, our focus is on encouraging dialogue between the clubs to resolve any disputes or avoid any disagreements. Breaches of the regulations can result in disciplinary proceedings being opened."