Parliament House officials have blamed a "technical problem" for an incorrect time stamp being on a media release issued by Opposition Leader Tony Abbott.

Mr Abbott released a lengthy statement about the sexual harassment case against Peter Slipper in April, demanding the Prime Minister remove him from the Speaker's position.

Federal Court judge Steven Rares last week dismissed the case, declaring it to be an abuse of process and politically motivated to advance the interests of the Liberal National Party and former Howard government minister Mal Brough.

Mr Abbott has consistently said he had "no specific knowledge" about the court case until it was revealed in the media, but Labor ministers have questioned that claim.

A time stamp attached to Mr Abbott's press statement appears to show the document was created at 11:08pm the day before the story was published, something his office strenuously denies.

A spokeswoman for the Department of Parliamentary Services (DPS) has told the ABC that technical staff have examined the document and believe the time stamp is incorrect.

"The time on the date stamp is 10 hours behind AEST due to a technical problem," the spokeswoman said in a statement.

"The Parliamentary Computing Network uses Coordinated Universal Time (UTC) on its computers.

"Normally, the time stamp format for this is 'UTC time + offset for local time zone'.

"In this case, the local time information was replaced by a 'z'.

"As a result, the offset for the local time zone wasn't factored in.

"The same problem has occurred with other documents created on this computer."

The ABC has been shown the Coalition's computer system, which appears to show similar problems with the time stamps on other documents.

The DPS spokeswoman says the department is still investigating the cause of the problem, but says it is the first time the issue has been brought to their attention.

Mr Abbott's office contacted the department's help desk last Thursday after receiving questions from journalists about the apparent contradiction in the time stamp.

The Government is continuing to pursue Mr Abbott over the failed sexual harassment case, demanding the Opposition Leader explain what he means when saying he had no "specific" knowledge.

Mr Abbott last week rejected calls to dump Mr Brough, who has been preselected as the LNP's candidate for Mr Slipper's seat of Fisher on Queensland's Sunshine Coast.