The IAAF will consider expelling Russia from track and field if "dramatic progress" is not made on anti-doping in the next five months.
A ban on clean athletes from the country competing as neutrals could also be implemented after the council of the sport's world governing body heard from its Taskforce investigating Russia's problems at a meeting in Birmingham, England, on Tuesday.
Rune Andersen, the independent chairman of the Taskforce, said afterwards that there were at least four outstanding issues, and the possibility of reinstatement at this stage had been rejected -- the biggest of which was the refusal of Russian authorities to acknowledge the institutional doping uncovered by the McLaren Report and the Schmid Commission.
"For us, we just need to get that acknowledgement because if we don't, we cannot move forward," he said after calling for an urgent meeting with the country's officials. "It's impossible."
IAAF president Sebastian Coe described the possibility of expulsion as the "ultimate sanction", and he has given Russia until the next IAAF council meeting in July to address that and other issues including a lack of an adequate testing plan for Russian athletes this year.
"The recommendation from the taskforce, which was unanimously accepted, was that we can't just sit here if there are still gaps in that verification criteria forever and a day," said Coe. "It is a costly process, it is time consuming."
On the possibility of expulsion, he added: "It's in nobody's interest to be sitting here in no-man's land waiting for a minor tweak here, a minor tweak there. There is no ambiguity about the criteria.
"We want that country back in the fold and we want their athletes. The world needs to know their athletes are in a system of confidence and trust."
Coe was accused this week of misleading a British parliamentary inquiry into doping and, under repeated questioning, suggested the digital, culture, media and sports committee's report which made the claim had been misleading.
Asked whether he accepted the report had damaged his and the IAAF's reputation, he said: "No. I can't account for answers that I gave to that select committee session which have been attached to entirely different questions, but that will be the response, of course, that we make to the select committee."
The council also agreed to complete new regulations to limit the amount of natural testosterone females are allowed to produce to compete in track events from 400 meters to 1 mile. It plans to have these approved by CAS and implemented by the beginning of November.
Transfers of national allegiance were also addressed with rules due to be drawn up before July's meeting and the current freeze remaining until then.