Bolton have become the second club to demand compensation from Barcelona over the transfer of Marcos Alonso last summer, according to reports in Spain.

Fourth-tier Spanish outfit Union Adarve accused Barcelona of fraud and filed a complaint to FIFA last month after allegedly learning that they deserved compensation from the LaLiga giants following Alonso's free transfer at the start of the season.

The left-back arrived at the Nou Camp last September shortly after Chelsea terminated his contract, reportedly taking a sizeable pay cut in order to sign for Barcelona amid their ongoing financial difficulties.

Union Adarve, who he represented as a youth player, claimed that they should have received £91,000 (€103,000) as part of the deal - and now League One outfit Bolton have come forward.

Alonso represented Bolton between 2010 and 2013, before the Spaniard moved to Fiorentina on a free transfer.

Bolton have become the second club to demand compensation from Barcelona over the transfer of Marcos Alonso - after Union Adarve accused the Spanish giants of fraud last month

According to Mundo Deportivo, Bolton believe they are 'entitled to compensation' over his 'training rights'. It is not yet known whether their appeal has any connection to Union Adarve's claim earlier this year.

The Spanish side reportedly claimed they have 'evidence of meetings' between Barcelona and Chelsea, which show that the Alonso deal was linked to Pierre-Emerick Aubameyang's move to Stamford Bridge last summer.

The Alonso saga is the latest legal battle to plague Barcelona in recent times. Spanish wonderkid Gavi could leave the club for free in the summer, after a court ruled in favour of LaLiga blocking the registration of his new contract and reverting his status to an academy player.

Meanwhile, Barcelona are facing a new legal threat from UEFA, including a possible Champions League ban, after the governing body learned that the club has allegedly paid millions of dollars to companies linked to a Spanish refereeing official.