Fairfax Media understands the national competition tribunal harbours serious doubts over whether it has the power to reconsider the high-profile Tabcorp-Tatts merger case, after the Federal Court found the original approval decision was potentially flawed and warranted a review.

In a letter on Friday morning, tribunal president Justice John Middleton flagged concerns that a time limit contained in legislation meant the tribunal may not have "jurisdiction" to hear the matter again.

The letter raised the possibility of Tabcorp having to file a "new application" to have the merger bid reviewed for approval.

Tabcorp and Tatts, the two biggest gambling companies in the country, have been pressing ahead with their merger bid after winning approval from the Australian Competition Tribunal in June. A shareholder vote is set down for October 28, and they have told the market they intend to have the merger finalised by November 1.

But the merger plans were disrupted this week when the Federal Court ruled in favour of the Australian Competition and Consumer Commission (ACCC) after it rasied concerns about the immense market power the merged entity would command, and the subsequent lessening of competition.

At a directions hearing at the tribunal on Tuesday, Tabcorp will argue that the tribunal has legal grounds to hear the case again.

"Tabcorp will be arguing that the tribunal does have the jurisdiction as the full Federal Court authority says the time limit is satisfied if the original decision was made in that time frame," a spokesman said.

The ACCC declined to comment on the latest developments.

The Tabcorp-Tatts merger has been under a cloud ever since the two appeals by the ACCC and rival betting operator CrownBet were lodged in July, but Tabcorp has consistently told shareholders it was "committed to the transaction" and confident of delivering the deal.

CrownBet, which also also fought to have the original approval reviewed, welcomed the court's ruling on Wednesday.

In a statement to the stock market on Friday, Tabcorp announced it had, after 10 months, obtained all necessary approvals of the relevant state and territory gambling regulatory authorities.

"Tabcorp has engaged with the various gambling regulatory authorities over the past 10 months, in order to satisfy the requisite requirements and secure the relevant approvals in order to implement the transaction," the statement said.

"The necessary pre-implementation notifications have been provided and the probity assessments for the proposed combined group, as well as its subsidiaries, directors, officers and 'associates' have been completed."