The 28-year-old Denmark international sealed a return to his boyhood club Brondby on Saturday after turning down a number of offers to remain in the Premier League.
And Agger, who joined Liverpool in a £5m deal from the Danish club in 2006, thanked the Reds and its supporters for helping the centre-half grow as a person and a player.
“Liverpool has been such a big part of my life and my family’s lives for so long that leaving is extremely difficult,” Agger wrote in his open letter published by Liverpool Echo.
“I’ll start by saying that Liverpool fans constantly keep surprising me. Since the news broke about the transfer, I have received so many positive messages and well-wishing for the future – not just from supporters in Liverpool but across the world.
“My family and I have always felt your backing, it is something unique to this football club, this city and our supporters – it’s been a privilege to have represented this club and I’m forever thankful for everything I have learnt during my time here.
“When I joined this great club, I came here as a 21 year old boy with a lot to learn. Liverpool has helped me grow up and shape me into the man I am today. I’m proud of who I’ve become and I wouldn’t be the person I am today without my time at Liverpool.
“I’ve been honoured to live in this close knit city and my experiences as a Liverpudlian are unforgettable. I’d finally like to wish the club all the best for this season. I’ll be supporting you every step of the way, as will millions of others. You’ll Never Walk Alone.”
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