Lord Coe raises concerns around Michael Johnson's Grand Slam Track with athletes still yet to be paid for first meet in April

World Athletics boss Lord Coe has voiced concerns about the conduct of Michael Johnson's Grand Slam Track, with athletes still waiting to be paid prize money months on from the competition.

Johnson launched a new track series earlier this year, offering stars record prize pots of $100,000 (£74,200) for winning their category at one of the four scheduled meets.

However, Grand Slam Track participants – including Britain's Zharnel Hughes - have still not received cash they were promised from the first event, which was held in the Jamaican capital of Kingston at the start of April.

Money is also owed from the meets in the US cities of Miami and Philadelphia. The fourth event, which was planned for Los Angeles last month, was cancelled at late notice.

'This is not a good situation,' admitted World Athletics president Coe, whose governing body were not involved in the launch of Johnson's league and have not spoken to the US legend for 'several months'.

'It's a start-up, but the athletes do need paying. Conduct in our sport is important to us. We are following this closely. I've had conversations with individual athletes, athlete representatives and even meeting directors on this.

'It was in everybody's interest for something like this to be successful. But we were very clear that this had to be done properly and executed properly. For these things to work, they can't be vanity projects. They have to be suffused in practicality and deliverability.'

Sources at Grand Slam Track insist athletes will be paid their earnings from Kingston by the end of this month, with cash from the other events following later this year.

World Athletics chief executive Jon Ridgeon added: 'Grand Slam Track have asked for a little bit of time. Hopefully, in that time, it will be concluded.

'It just shows you how hard it is to launch new stuff. In any sport, it's really hard.'