The Russian Athletics Federation (RusAF) claimed the IAAF had rejected their applications because the athletes had not been part of the approved drug testing pool for a long enough period.

In December the IAAF had announced a new list of criteria for Russian athletes to compete under as neutrals in 2018.

This included being part of the IAAF's registered testing pool for a period of at least 12 months. 

Russian athletes have been permitted to compete as neutral athletes since the 2016 Olympic Games in Rio de Janeiro following the decision by the IAAF in November 2015 to suspend the country from international competition.

It followed the publication of a report commissioned by the World Anti-Doping Agency and chaired by International Olympic Committee member Richard Pound of widespread doping in Russian athletics. 

The IAAF announced last month that out of 83 Russian athletes who had applied to compete in 2018 as an Authorised Neutral Athlete (ANA) only 18 had been successful. 

The decision had been taken by the IAAF Doping Review Board, consisting of America's Robert Hersh, The Netherlands' Sylvia Barlaq and Finland's Antti Pihlakoski, but it was unclear the status of the remaining athletes.

RusAF have now confirmed, though, Russia's official state news agency TASS has reported, that at least 18 will not be eligible to compete as ANA this year.

That means they will miss next month's IAAF World Indoor Championships in Birmingham and the European Championships in Berlin in August. 

Among who are cleared to compete this year, though, is high jumper Maria Lasitskene, winner of the gold medal at the IAAF World Championships in London last year. 

A similar system was set up by the International Olympic Committee before the Winter Olympic Games, currently taking place here, to decide which Russian athletes would be eligible to compete.

Being part of a recognised drug-testing pool was one of the key components. 

A total of 168 competitors are taking part in the Olympic Athletes from Russia team.