Millwall attacker Aiden O'Brien is being watched by Premier League clubs.

Sky Sports says West Ham United, Everton, Crystal Palace and Swansea City are all thought to have had O'Brien watched in recent weeks.

Several Championship clubs including Bournemouth, Brentford, Ipswich and Nottingham Forest are also monitoring on his situation.

O'Brien, 21, is entering the final year of his contract at the Den and Millwall are bracing themselves for interest in the attacker this summer.