Scott McGregor will continue to play the detective, who has been investigating the attempted murder of Paul Robinson.
A source told the Daily Star Sunday: "Scott McGregor, who plays Mark, was brought in for a few weeks to cover the investigation into Paul's attack.
"But the girls went mad for him. We haven't seen a reaction like it for years, so his contract was extended until the end of next year.
"He's got some great stuff coming up and everyone is looking forward to how the viewers react when they see what he gets up to in 2011. There's going to be another hot relationship hitting Ramsay Street."
