Chelsea and Arsenal are set to play in Baku on May 29, but both teams have returned over half of their combined allocation of 12,000 tickets for the Europa League final due to the difficulty and great expense for fans traveling to Azerbaijan. 

A lack of direct flights between London and Baku means supporters face costs of over 1,000 British pounds (1,300 U.S. dollars) just to make the 5,000-mile round trip before tickets and accommodation are taken into account.

Arsenal had initially complained over their small allocation, but confirmed that they have returned 2,200 tickets for the Gunners' first European final in 13 years.

Meanwhile, Chelsea have sold just 2,000 of their 6,000 allocation.

UEFA denied reports that sponsors had also returned tickets and said they were confident that local fans will snap up the spare tickets to ensure there is a capacity crowd at the 68,000 Olympic Stadium.

"The majority of these tickets have already been sold to local fans in Azerbaijan and we are confident that the remaining ones will also be sold as demand is very high," UEFA said in a statement.

The Chelsea Supporters' Trust (CST) joined other supporters' groups in criticizing UEFA for the location of the final.

"Baku is a totally unsuitable location for a major European final. The combination of cost, complexity in regard to travel arrangements and time off work has massively reduced the traveling support, including those who loyally and ordinarily go to all home, away and European matches," said the CST in a statement.

However, UEFA president Aleksander Ceferin has defended the decision to host the final in Baku.

"There are people who live there who love football," the 51-year-old told German news magazine Der Spiegel.

Arsenal midfielder Henrikh Mkhitaryan will also not travel to the final due to safety fears, as his native country Armenia has political conflicts with Azerbaijan.