Liverpool have been handed encouragement in their attempt to sign Naby Keïta from RB Leipzig, although the German club have indicated they are not prepared to let the Guinea international leave for less than £70m.

Jürgen Klopp has identified the 22-year-old central midfielder as a key target after completing the £36.9m club record signing of the Egypt international Mohamed Salah from Roma last week, with Southampton’s Virgil van Dijk also still wanted by the Liverpool manager despite the club publicly apologising this month over their approach for the Holland defender and saying they had ended their interest.

Keïta, who has refused to sign a new contract with Leipzig despite holding talks at the end of the season, impressed as the promoted side finished as runners-up in the Bundesliga to secure qualification for the Champions League for the first time. He has three years remaining of the deal signed when he moved last summer from their sister club Red Bull Salzburg – where the Liverpool forward Sadio Mané spent two years before joining Southampton in 2014 – but is understood to have indicated his desire to leave should the club’s valuation be met.

Despite Leipzig’s sporting director, Ralf Rangnick, and the chief executive, Oliver Mintzlaff, publicly insisting neither Keïta nor the Sweden forward Emil Forsberg will be sold, Leipzig are believed to be demanding £70m for Keïta, who joined for around £10m last year.

“It would be negligent to give away one of our key players now,” Mintzlaff said last week. “Emil and Naby are both extremely talented players with a lot of potential. We are delighted that we as a club can keep up with their development and that we can prove ourselves in the Champions League in the upcoming season.”

Liverpool are considering offering a deal worth up to £50m for Keïta, a box-to-box midfielder who scored eight goals and provided seven assists in his first Bundesliga season. Whether they are prepared to increase that remains to be seen, particularly with Southampton now valuing Van Dijk at £70m despite the defender having indicated his preference is to move to Anfield.

Chelsea and Manchester City have also registered interest in the 25-year-old Van Dijk as Antonio Conte and Pep Guardiola search for defensive reinforcements.