SANZAAR, made up of the South African, New Zealand, Australian and Argentine rugby unions, met in London two weeks ago to address widespread criticism of the unwieldy 18-team format of its provincial competition.
Fevered speculation about the shape of the agreement followed with media reports in Australia and South Africa indicating that a total of up to three teams from those two countries would be axed for 2018.
SANZAAR, though, has failed to provide any further information and left the guesswork to grow unchecked.
"I accept that, I think it was called the 'golden silence' in one media report, is frustrating but (until) we have confirmation I can't say any more," Tew told reporters on a conference call on Thursday.
"There have been some tough decisions taken. But they require consultation and sign-off from a large number of parties and that work is underway and largely out of our hands."
Media reports indicate that the teams most at threat are Australia's Western Force, ACT Brumbies and Melbourne Rebels as well as South Africa's Kings and Cheetahs franchises.
A 16-team competition, or a reversion to the 15-team format that prevailed before 2016, would allow organisers to axe the confusing conference system that has created an imbalanced playing schedule and ensure a straight round-robin format.
Tew would not be drawn on the substance of any changes, although he did say he was happy with the new format.
"We are very comfortable that the decisions made in principle in London will be good for the competition and good for New Zealand rugby," he added.
"We would all have empathy for anyone who is subject to a change process but sometimes its necessary to make tough decisions and you have to work through it."
Tew's comments came hours after the coach of the Perth-based Force said the uncertainty was making player recruitment and retention for beyond this season very difficult.
"The frustrating thing is we haven't been able to finalise those things because of the uncertainty with SANZAAR," Dave Wessels told reporters in Perth.
"That leaves the rest of our group feeling a bit upset and vulnerable...."
Wessels urged SANZAAR to finalise discussions as soon as possible to end the uncertainty not only for players but for administrative, coaching and support staff.
"In behind this are people with families," Wessels said.
"That's everyone who works in our organisation, as well as the Rebels and Brumbies. And for that matter the Cheetahs and Kings.
"So you're talking about a substantial amount of people who are affected by this uncertainty. The sooner it can be settled, the better for everyone."
(Reporting by Greg Stutchbury; Editing by Nick Mulvenney)
