The hunt for the mole who leaked three confidential reviews into England's World Cup campaign will continue into next week if the Rugby Football Union's council agrees at its meeting on Friday that cost is no object in tracking down the source.

The firm of investigators hired by the RFU last week to track down the source of the leak, Monitor Quest, has drawn up a preliminary report for the council to consider. The former Scotland Yard detectives who are part of the investigation, including a forensic computer specialist, have gone through computers at Twickenham and spoken to staff, elected members of the governing body and personal assistants.

The council will be asked if it is prepared to sanction a bill that could run into tens of thousands of pounds if hard drives are to be scrutinised and the records of mobile phones, either owned or paid for by the RFU, are to be examined.

The union is under pressure from England players and management to find the culprit, not least because if he or she is never identified then trust in the organisation will not be restored. Some candidates for the position of chief executive have expressed concern at being part of an organisation where someone is prepared to disclose confidential, and damaging, information to the media.

The RFU had hoped to name a new chief executive as the replacement for John Steele, who was sacked last June, by the middle of this month, but it has set a target date of 31 December, admitting the appointment may not be made until the new year. Jeff Blackett, the union's chief disciplinary officer, said: "This was a very serious leak and, as the RFU looks to put the events of this year behind it and restore an atmosphere of trust, it is important that the person responsible is identified.

"The investigators are confident they can track down the source and I will be providing the council with a full update on how their inquiries have progressed."

The RFU is under pressure from its two partners on the professional game board, Premiership Rugby and the Rugby Players' Association, to identify the source of the leak. The board was considering the reviews when they were made available to the Times with the result that sensitive information, which was provided on a confidential basis, became public.

A number of the England squad had reservations about taking part in the review because they were concerned that what they said or wrote would be leaked, even though all contributions were made on an anonymous basis. Two refused to take part and one returned a blank questionnaire. The RPA is unlikely to sanction participation in future reviews if the mole goes undetected.

Damian Hopley, the chief executive of the RPA, last week described the leaking of the documents as an absolute disgrace and an outrage. He said: "If England wants to regain its status as a respected rugby nation, it is imperative that we stop the rot at the top of the game and show some much needed integrity. What example does this set to the game? It is an absolute disgrace.

"It was the lack of faith in the system and process being confidential that saw many players shy away from completing the RFU questionnaires in the first place and, perhaps not surprisingly, their mistrust has been proven to be correct. We cannot ignore that once again there has been a serious breach of confidentiality.

"We are demanding a detailed investigation to track down the source of the leak and deal appropriately with that person. If we are serious about destroying the porous culture in our game, then we need to introduce tougher security measures to weed out these self-serving people once and for all."

Money is no object for the RFU, which last month reported a profit of more than £8m. "The leaks were inexcusable," Ian Metcalfe, the professional game board chairman, said.

"We want to find out why it happened and to stop it occurring in the future, something we will need to do to regain the trust of the players."