Queens Park Rangers have made an appeal to supporters for information regarding a coin throwing incident at Loftus Road on Saturday afternoon.
Assistant referee Stuart Burt was struck on the back of the neck by an object thrown from the Ellerslie Road Stand, which holds QPR fans.
"Such behaviour is simply not acceptable at Loftus Road, or anywhere else for that matter," QPR's chief executive Philip Beard told the club's official website.
"As a club, we will do everything possible to prevent such incidents happening again.
"The club appeals to any fans who saw the coin-throwing incident to come forward and assist our enquiries."
The R's have vowed to suspend anyone found guilty for life.
