The two parties reached the agreement on Thursday, avoiding the need for an additional hearing on January 11 to determine an injunction application.

STT had already agreed to halt logging in 19 coupes from October, but now additional coupes have been added after negotiations this week.

Dr Brown said some of the coupes were hundreds of hectares in size, and included areas where ecologists had documented swift parrots in recent months.

"It's a reprieve," he said.

"It's not total, mind you, and the logging in Tasmania is still quite extensive and the swift parrot moves around, but because of the abundant eucalypt blossoming in the Eastern Tiers, they have concentrated on feeding, breeding and nesting there.

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"It gives them a reprieve that they would not have got had my foundation not firstly engaged, taken up the scientific evidence that was available and decided to take both legal action and peaceful citizen's action."

BBF submitted an injunction request on the coupes on December 18, which has now been withdrawn as a result of the agreement.

Conservation ecologist Matthew Webb had earlier submitted an affidavit to the Federal Court in which he detailed seeing swift parrots in two coupes in the Eastern Tiers where gums were flowering, but logging was imminent.

"In my opinion, swift parrots are present in these coupes and in the surrounding area because they are either nesting, or searching for suitable hollows in which to nest, and/or feeding," he wrote.

These coupes were targeted in protest action by the Bob Brown Foundation before Christmas, in which Dr Brown was twice arrested and charged with trespass. He will appear in court on March 31.

A spokesperson for STT said a stay on forestry activity in the coupes was agreed to in order to avoid the hearing on Monday, after originally stating it would resume logging from next week.

"Sustainable Timber Tasmania has proactively and voluntarily offered to provide an undertaking to not conduct forestry activity in these coupes until determination of the court case by the Full Court which is expected in February 2021," the spokesperson said.

"The undertaking is given entirely without admission and solely for the purpose of avoiding a costly and time consuming dispute regarding an injunction.

"This will provide operational certainty for two harvesting contractors, reduce operational disruption and costs for our contractors.

"The undertaking has been offered in consultation with industry and Sustainable Timber Tasmania will continue to meet supply commitments to its customers."

The Federal Court is expected to reach a decision in Dr Brown's case against the Tasmanian Regional Forest Agreement in February.