Liverpool have bid €25m (£21.8m) for the Atlético Madrid striker Diego Costa as the manager, Brendan Rodgers, looks to add quality to his squad before the transfer deadline.

The Anfield club have moved for the twice-capped Brazil international despite ongoing uncertainty over Luis Suárez's future and having been frustrated on several big-money signings this summer. Liverpool's offer is understood to meet the release clause in Costa's contract and the club hope the 24-year-old, and Atlético, will agree to a deal swiftly.

That appears unlikely, however, with Atlético denying they had received the offer on Thursday and telling the Spanish newspaper AS that the striker was not for sale. Arsenal, the only club to have made an offer for Suárez, have also been linked with the Brazilian this summer.

Costa is a controversial figure in Spain with a chequered disciplinary record but enjoyed his most productive campaign at Atlético last season, scoring 10 goals in 31 league appearances and a total of 20 goals in 44 games. He had been expected to play a bigger role at Vicente Calderón this season following the departure of Radamel Falcao to Monaco. However, the arrival of David Villa and Léo Baptistão cast doubt on his claims to a regular first-team place and the coach, Diego Simeone, has indicated Atlético would consider allowing Costa to leave too.

Rodgers is determined to improve Liverpool's attack irrespective of whether Suárez stays or goes, and with the club refusing to countenance his sale to Arsenal for a sum of £40,000,001. Arsenal have not returned with a higher offer since their second bid was rejected more than a week ago and the striker has not sought Premier League intervention over a disputed clause in his Liverpool contract.

"They have to be of the right quality, that's the bottom line," said Rodgers of his remaining transfer targets for this window. "We've got money to spend on getting that quality in, but if it's not available I won't waste it for the sake of bringing a player in. We're really working hard to bring in the type of profile that can really help us push on. We just need to see if that's available and affordable."