Portsmouth have placed forwards Adam McGurk, Kal Naismith and Matt Tubbs on the transfer list.
Tubbs joined National League side Eastleigh on loan in February, while McGurk and Naismith both featured in Sunday's League Two play-off semi-final defeat by Plymouth.
Defender Ben Davies and midfielder Danny Hollands remain in talks over new contracts at the club.
Ben Close, Adam May and Ben Tollitt have triggered one-year extensions.
Pompey have also announced Brian Murphy, Chad Field and Snorre Nilsen have been released following the expiration of their contracts.
Youngsters Alex Bass, Calvin Davies and Christian Oxlade-Chamberlain were offered one-year professional deals in April.