Ireland striker Aiden O'Brien is looking for a new club after Millwall confirmed they will not be offering him a new contract.
The 26-year-old Londoner has spent his entire professional career on the books of Millwall, establishing himself as a first team player following a series of loan moves.
O'Brien had struggled for gametime with the Championship promotion chasers this term and manager Gary Rowett has confirmed the decision to let O'Brien go.
Injury problems have contributed to his absence since February. O'Brien has scored 44 goals for the Lions spread across stints in League One and the Championship.
"Aiden came to see me a while ago to ask about his situation and I couldn't really give him anything definitive," said Rowett.
"He really wanted a steer and I told him that as we stand I think he has to move on and play. I think he understands that.
"He's been at Millwall a long time and the fact he has been injured towards the end of this season has been tough for him. He hasn't had those last few games with the team and in front of the fans. It's a really tough ending for him.
"Every player gets to a point where they need a change and a fresh environment - for the good of Aiden's career he probably needs that."
Meanwhile, Galwegian Joe Shaughnessy has returned to the Scottish top flight to sign for the St Mirren side managed by Waterford native Jim Goodwin.
The former Aberdeen and St Johnstone defender spent last term with Southend.