Russia is facing an even longer ban from international athletics because of its failure to tackle its tainted doping system, Sebastian Coe has warned.

The Russian Athletics Federation has been barred from international competition since November 2015. It will miss the world championships in London in August having also being excluded from the Rio Olympics but had hoped it would be reinstated by the end of 2017. The IAAF president hinted the possibility was now remote following the latest report by an International Association of Athletics Federations taskforce, which said it was “concerned” that little attempt at reform had been made.

Lord Coe said: “The task force was disappointed with the lack of progress. Testing is still far too limited, the Russian investigative committee is still refusing to hand over athlete biological passport samples for independent testing, we still have got athletes in closed cities that are difficult or impossible to get to and we have got coaches from a tainted system still plying their trade.

“There is no reason why better progress has not been made. The criterion we laid down is the criterion that stands and Rusaf should be under no illusion at all that we will stick to this. We were dealing with a pathology that was seismic. Over the course of the previous four or five years we had over 130 positive tests and suspensions. This was not something we could turn a blind eye too. And we will continue to be tough. This is non-negotiable.”

A handful of Russian athletes, including the reigning world champions Sergey Shubenkov and Maria Kuchina, will be allowed to compete under a neutral flag in the world championships having proved to the IAAF they have been tested regularly outside Russia. Coe said Russia was still not doing enough to show it was undertaking the fundamental reform necessary for reinstatement.

Coe pointed out the head coach of Russian Athletics had “effectively refused to sign their own pledge to clean athletics”, while the IAAF taskforce also noted with concern that the Russian 1500m runner Andrey Dmitriev, who had spoken out about the continuing culture of doping in Russian track and field, had been criticised by the deputy prime minister, Vitaly Mutko, and the new head of the Russian Anti-Doping Agency, Yelena Isinbayeva.

Coe warned that unless stronger steps were taken, he was prepared to take further action against Russia when the IAAF council meets again in July. This is not arcane maritime law,” he said. “There will come a point where the council will take a judgment about what are the next steps. But in the key areas there are some very, very big gaps that still need to be bridged.”

Speaking at the IAAF council meeting in London, Coe also appeared to give his backing to the next generation of marathon shoes, despite concerns some may contain illegal springs.

The IAAF’s technological committee is investigating Nike’s new Zoom Vaporfly Elite shoe, which will be used by athletes attempting to break two hours for the marathon in Italy next month, owing to fears a special carbon fibre plate in the sole breaks the sport’s rules.

Coe said that, as long as the technology was accessible to all, the shoes should be “welcomed”. He added: “We do need to embrace new technology. We do need to make sure design is there to allow athletes to train harder and reduce the chances of injuries. As long as that is the case, then I tend to come on the side of the athletes.”

Coe also confirmed the IAAF would not be scrapping the 50km race walk from the 2020 Olympics in Tokyo but did hint that his organisation may look to make changes to the programme for the 2024 Games.

More than 60 competitors had signed a petition to the IAAF stressing their opposition at plans to drop an event that has featured on every Olympic programme since Los Angeles 1932, apart from Montreal 1976. But that threat has now been eased at least for the time being.

“We will continue to evolve and innovate but the proposals that are being developed and consulted on will be introduced post-2020,” Coe said. “And they will be consulted on widely within and outside the sport.”