The IAAF said on Monday that it will maintain its ban on Russian athletes over doping that it imposed in 2015, following a council meeting of top officials in Qatar.
Rune Andersen, head of the doping task force for the International Association of Athletics Federations, said two issues remained unresolved -- the examination of data received from the Moscow anti-doping laboratory and the issue of outstanding costs being sought from Russia because of the scandal.
"Two key issues remain outstanding," said Andersen at a press conference in Doha. "These need to be resolved."
He also said his task force was looking into claims that coaches from the discredited Russian athletics regime were still involved in the sport which, Andersen said, "run counter to assurances" received from Moscow.
Asked if this latest extension of the ban meant Russian athletes would not be able to compete under the flag at this year's world championships in Doha in September and October, Andersen said there was still time but conditions "have to be met" by Russia.
IAAF head Sebastian Coe refused to be drawn on whether Russia had time to enter the worlds, saying he didn't "want to speculate" on the country's chances.
"Let's see where this process takes us. And then make whatever adjustments we might need to," Coe said in a conference call with reporters.
"At the moment it's important we don't start speculating. It will be dependent on the recommendations given by the task force."
Responding to the IAAF's concerns, Russian Sports Minister Pavel Kolobkov insisted that any coach found to have been involved in doping was barred from working with the national team.
"The coaches and the athletes who have been banned for doping are automatically excluded from the national squad participants' list," Kolobkov said.
Dmitry Shlyakhtin, the head of the All-Russian Athletics Federation, said the claims about the coaches and the issue of the payment of outstanding debts would be discussed at a meeting with Andersen later this monnth.
"I'm confident that we will find the solution that will settle the situation," he added.
The IAAF suspended Russia in November 2015 after the eruption of a vast state-sponsored doping scandal.
The decision to keep the ban in place was the 10th time the IAAF has turned down Russia's appeal for reinstatement, having requested the same assurances when it upheld the ban in December.
A team from the World Anti-Doping Agency (WADA) gained access to the Moscow laboratory at the centre of the scandal in January and officials are working their way through the mass of data recovered.
Although the International Biathlon Federation still excludes Russia, the IAAF is the last of the high-profile international sports bodies to ban athletes from competing under the Russian flag, although many Russians are allowed to compete under a neutral banner.
The International Olympic Committee lifted their suspension of the Russian Olympic Committee a year ago and WADA reinstated Russia in September.
Russia's Paralympic ban was lifted in early February.
The fallout from the scandal continues.
A dozen more Russian athletes were suspended on February 1 based on the revelations of the McLaren report on the doping scandal. The 12 included high jumper Ivan Ukhov who was stripped of his 2012 Olympic gold.