Raheem Sterling, Adam Lallana and Jordan Henderson during England's training session before the Peru clash. Getty Images

Liverpool are preparing an improved offer in signing Southampton midfielder Adam Lallana in the summer transfer window, according to the Metro.

The report claims Brendan Rodgers' side made a £20m bid for the services of the England international. However, the Merseyside club's offer was turned down by the Saints as they felt the Reds' offer was not meeting their expectations.

Liverpool have made Lallana a top priority target in the coming transfer window and are ready to improve their offer. The Premier League runners-up are preparing a £26m bid in bringing the midfielder to Anfield.

The amount will be paid to Southampton in two instalments due to the heavy fee involved in the potential transfer. Lallana has been included in Roy Hodgson's 23-man shortlist for the summer event. Rodgers is keen to secure the deal before Lallana boards the plane to Brazil for the World Cup with the England national team.

The Reds are aware of Tottenham Hotspur's threat in landing Lallana. The White Hart Lane club appointed former Southampton boss Mauricio Pochettino as their new manager on a five-year deal.

The Argentine manager's arrival at North London has seen the Spurs being linked with a shock move in signing the Southampton star. However, without Champions League football, it would be difficult for Pochettino to tempt Lallana to join him at White Hart Lane.

The 26-year-old has already expressed his desire to feature in Europe's top club competition next season.

"I'm ambitious. I have aspirations to play in the Champions League. Ever since I've played international football, you realise there's that other level to play at. It would be great," Lallana revealed.

"I went to a couple of the Champions League games last year and the feeling you get, the buzz, it's an unbelievable atmosphere. It's definitely a goal of mine to play in the Champions League."

Meanwhile, Liverpool are closing in on securing a deal for Lallana's Southampton and England teammate Rickie Lambert. The 32-year-old is set to complete his move to Anfield on a £4m transfer.