The news puts to bed any lingering fears that Agger could be snapped up by Barca - who have been linked with both him and Chelsea's David Luiz - this summer.
Reds manager Brendan Rodgers told LFC TV: "The job of the captain and vice-captain here at Liverpool is very, very important. I wanted to give myself time over the course of the pre-season to assess a number of the players and obviously Daniel was one of them.
"His loyalty and his passion for Liverpool is second to none. And if you add that on to his footballing qualities, then I think it's a good choice for everybody."
Earlier, Rodgers spoke of the defender's unswerving loyalty to Anfield.
“If we’re talking about loyalty, he was one of the first players that I spoke to when I became the manager. At the time, there were a number of big clubs looking to sign Daniel," he said.
“But he gave me his word that for as long as I wanted him to be at Liverpool, he would be at Liverpool. He has never swayed from that.
“He has an unswerving commitment to Liverpool which is so refreshing. His loyalty to the club is incredible.”
Agger, who has scored 12 goals for the Anfield club, played in the 2007 Champions League final and helped the Reds win the 2012 League Cup before signing a new long-term contract last October.
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