The Spaniard has been linked with Liverpool for a number of months and, according to the Daily Express, the Reds are considering making a formal approach for the player.
Liverpool, it is claimed, offered £3 million for Capel earlier this summer, although must double that fee if they hope to secure his signature, as Brendan Rodgers strives to make further reinforcements.
Following the sale of Stewart Downing and the expected transfer of Willian to Tottenham, Liverpool may be encouraged to pursue more attacking options - and Capel is reported to be among them.
The 25-year-old has also been linked with Marseille, although it is unclear if the French club are serious about their interest in Capel.
Should Capel secure a transfer to Liverpool, he would become the third attacking recruit the Reds have made this summer, following the acquisitions of fellow Spaniard's Iago Aspas and Luis Alberto.
Liverpool have also signed goalkeeper Simon Mignolet from Sunderland, while they have bolstered their defence with Kolo Toure and Aly Cissokho.