Hamilton-Brown is a former England Under-19 captain
Sussex have given all-rounder Rory Hamilton-Brown permission to talk to Surrey over a move that would see him become captain at The Oval.
The 22-year-old, who has played just eight first-class games, moved to Hove from Surrey in 2008.
"We have no wish to see a player of Rory's potential leave the club," said Sussex chairman Jim May.
"However, we recognise that it is appropriate to give Rory time to talk to Surrey about their opportunity."
Hamilton-Brown made his debut for Surrey in 2005 and moved to Hove three years later where he played under then-Sussex captain Chris Adams, who is now cricket manager at The Oval.
The off-spinning all-rounder has now been earmarked as a potential captain by Adams, who saw his side led by six different men last season.
Surrey's inquiry for the former Millfield School student, made on 1 December, was initially treated with disdain by May, who said: "The approach is unwelcome and the timing very unfortunate.
"Rory has very strong potential to develop an excellent career with Sussex, where we strongly believe his cricketing development will be best served."
Now, despite giving Hamilton-Brown permission to talk to Surrey, May has said that Sussex will also be offering him an extended deal.
"Our immediate aim is to agree an extended contract with him," said May. "At this stage, the club has granted permission to talk only.
"We remain strongly of the view that Rory's cricket development is best served by remaining at Sussex and we will be meeting him subsequent to his meetings with Surrey to discuss matters further."
Hamilton-Brown was part of the Sussex side that won the 2009 Twenty20 Cup and subsequently took part in the inaugural Champions League Twenty20.
In October, he was named in category B of the England performance squad for players identified as being one to three years away from the international team.
Former Surrey and England batsman Graham Thorpe, now the club's batting coach, believes whoever becomes captain will have a "big task on their hands" and need to be "a strong leader".
He said: "Chris Adams has known Rory from his time down at Sussex.
"When he was captain there he had him then so maybe it's something he saw in his personality to feel that he's a player that Surrey should be pursuing. We'll see what happens."