KEN Anderson has launched a broadside on Wanderers’ under-performing players after successive defeats against Leeds United and Birmingham City.

With Phil Parkinson’s side slipping back towards the bottom three over the Easter break, the Whites chairman stopped short of naming individuals but warned: “These players all know who they are and they need to step up their performance if they want to stay with us next season.”

Wanderers have 20 senior and development squad players out of contract in the summer – only five of which – Mark Beevers, Ben Alnwick, Sammy Ameobi, Karl Henry and Derik Osede - were in the starting line-up in the 1-0 defeat at the Macron on Tuesday night.

Of the other six, Jon Flanagan and Reece Burke are on loan, and Andy Taylor, Josh Vela, Adam Le Fondre and Will Buckley are contracted for at least another year.

Anderson’s unprecedented blast came via his regular website column, published in the light of Tuesday night’s disappointing display against Birmingham.

“As l have said previously the majority of our squad are playing for new contracts and evidently it is financially more rewarding for everyone concerned that we ensure we retain our Sky Bet Championship status,” he said.

“As they say, we are now at the business end of the season and it’s imperative that the squad as a whole gives 120 per cent in every game for the full game, not just in patches, and unfortunately this has not been the case for several players recently.”

Wanderers go to play-off chasing Derby County tomorrow looking to get back on track and with Parkinson hinting at shuffling his line-up.

Anderson also made his feelings abundantly clear ahead of the trip to Pride Park – a ground where Bolton has never claimed a league victory.

“l feel sure that the management team will look long and hard at our recent performances and maybe think it is time for change and select a team that are more than capable of going to Derby County on Saturday and getting a result,” he said.

“Obviously it’s a tough game and with all the top 10 teams still challenging for play-off places, there will be no let-up so we need to grind out match-winning performances as we did away to Sheffield United and at home to Bristol City and Aston Villa. That is the level of commitment now required.”