Fulham launched an official complaint to the Premier League on Thursday over Liverpool's conduct in their pursuit of American forward Clint Dempsey.
Liverpool boss Brendan Rodgers last month broke managerial protocol when he went public with his interest in Dempsey, prompting the Cottagers star to make it clear he wanted to move to Anfield.
But there has been no firm bid from Liverpool since then, leaving the player confused and Fulham boss Martin Jol furious.
Jol has left Dempsey out of his squad for Saturday's trip to Manchester United, having already dropped him for last weekend's victory over Norwich because he felt the player wasn't in the right frame of mind to perform.
The Dutchman criticised Liverpool's behaviour last week and the west London club have now followed up with a complaint to the Premier League.
"The Premier League has received a complaint from Fulham regarding certain comments made by Liverpool officials and is currently looking into the matter," a statement read.