Turner has already rejected a bid from WBA for Raynes

The European champions wanted a closer look at the 17-year-old, with a view to signing him on a permanent deal.

"Although he is still only young, Michael played 20 senior games for us last season," Turner told Stockport's official website.

"He is very much part of our first-team squad. I don't think it's right to let first-team players go on trial."

Turner said he wanted to protect his young player, who has already attracted attention from West Bromwich Albion.

"I've seen instances in the past when young players have returned from trials at big clubs with a big dent in confidence because a dream move didn't materialise," he said.