Liverpool have signed the 20-year-old forward Luis Alberto from Sevilla on a long-term contract, the club have confirmed.

Alberto, who came though the ranks at Sevilla, spent last season on loan at Barcelona B, scoring 11 times in the second division, but the Catalans did not take up their option to sign him permanently.

"We are all delighted that Luis has decided to join Liverpool," said the manager, Brendan Rodgers. "He has the correct footballing profile and mentality to be a Liverpool player. I look forward to working with him to develop his talent and he joins a group of young exciting players at our club."

Alberto added: "I feel very excited, I've never felt so excited before but I'm very happy. I think I am the happiest man on earth. I have come here to enjoy moments with the supporters – and I know the supporters will help me to never walk alone. I hope that between us all we can make this club one of the greatest in the world, once again."

Meanwhile, Liverpool have agreed a fee of just over £11m with Sunderland for the Belgium goalkeeper Simon Mignolet. Weeks of negotiation concluded with a deal for the 25-year-old, who is now scheduled to travel to Merseyside for a medical and discussion over personal terms early next week.