The Bulls have written to Huddersfield demanding a “substantial increase in compensation” for Craig Kopczak following the revelation that his move to the Giants was agreed last August.

Bradford claimed the Wales captain had been approached illegally by Huddersfield after he walked out on his hometown club on the eve of the penultimate match of last season.

At the suggestion of the Rugby Football League, Huddersfield paid the Bulls £20,000 compensation but Kopczak last week admitted he had agreed to join the Giants on August 8 – a full month before he quit Odsal.

The revelation came as Kopczak gave evidence under oath last week at Leeds High Court when former Huddersfield prop Keith Mason successfully argued that he had been unlawfully dismissed by the Giants.

The RFL’s initial probe into Kopczak’s controversial defection concluded Huddersfield had no case to answer.

However, Red Hall bosses have since said they would be “examining the evidence submitted in court to determine whether there was an illegal approach for Kopczak.”

And the Bulls have now confirmed they are seeking a substantial increase from the initial payment of £20,000 in compensation for a player who was contracted to the club until the end of this season.

Bulls honorary chairman Gerry Sutcliffe said: “People have lied to the RFL and they have lied to us.

“We’ve contacted Huddersfield and told them we don’t think they paid us the right amount of money.

“I think it’s terrible what happened and I think their conduct needs to be looked at during that difficult period for our club.

“I’ve officially contacted Blake Solly (RFL director of licensing and standards) and something, surely, has to happen because we can’t allow this kind of thing to carry on.”

Sutcliffe will push for an increased payment for Huddersfield and will await with interest to see what action, if any, the RFL take after they review the evidence given in court last week.

The Bradford South MP added: “What the RFL are saying to us is that it was a deal agreed between two clubs but they are also going to look at the transcript of the court hearing last week.

“They will deal with the people involved, I’m sure, but it doesn’t put us in any better position. Not unless we get a further substantial sum from Huddersfield.”

Sutcliffe is expected to take further questions on the Kopczak affair at tonight’s fans’ forum in the Coral Stand at 6.45pm.