Tottenham Hotspur will reportedly pay a €500,000 (£438,000, $558,000) fine to Espanyol if they opt against completing the signing of Pau Lopez from the La Liga side on permanent basis this summer.

Sport says that this would explain why the Catalan side recently turned down an offer from Spurs worth around €2m plus add-ons – despite the keeper only having 12 months remaining on his current contract with Quique Sanchez Flores' side.

The 22-year-old goalkeeper moved to White Hart Lane during last summer's transfer window after Spurs agreed to pay a fee of €600,000 to sign him on loan for the 2016-17 season. Tottenham also agreed to an option to make the move permanent for €7m at the end of the season.

Last month, IBTimes UK reported that Tottenham were trying to negotiate a cut-price deal because Lopez will be available on free transfer at the end of the 2017-2018 campaign. Spurs then launched a €2m offer which was immediacy rejected by Espanyol as the Catalans were demanding at least €4m to cash in on the Spain Under-21 international.

Later, reports claimed that Tottenham had decided to withdraw from negotiations after failing to convince Espanyol to reduce their demands.

Some could have then questioned the stubbornness of the La Liga side over a player who could walk away for free at the end of next season when his current deal expires.

But sources at Espanyol have now explained to Sport that the club have good reasons to reject the offer from Tottenham.

Sport says that "sources from the La Liga side" have confirmed that Spurs will need to pay them a €500,000 fine for failing to purchase the 'keeper due to a clause inserted in the loan deal that both clubs agreed last summer.

This means that Espanyol will receive a total of €1.1m for having had Lopez at Tottenham last season, having already been paid €600,000 for the initial loan.

Pau Lopez
Pau Lopez is currently in the Under 21 European Championship with Spain. Getty Images

Espanyol, meanwhile, would have only got around €1.4m if they had accepted the latest €2m offer from Tottenham as the agreement also stated that the €600,000 fee for the initial loan would have been withdrawn if Spurs made the move permanent.

The Catalan side believes that the offer from Spurs was therefore "unacceptable" and will instead keep Lopez in La Liga for one more season, unless there is a another U-turn in negotiations before the end of the transfer window.

Furthermore, Espanyol believe the risk is one worth taking as they are expected to offer Lopez a new deal in order to avoid losing him for nothing to Tottenham or any other club in the summer of 2018.