'Between 400 and 500' migrant worker deaths according to Qatar chief Hassan Al-Thawadi

Between 400 and 500 migrants have died as a result of development linked to the Qatar World Cup, the tournament's chief has claimed.

Hassan Al-Thawadi, secretary general of the Supreme Committee for Delivery and Legacy, gave the figures during an interview on TalkTV’s Piers Morgan Uncensored.

The issue of safety and treatment of migrant workers has been one of the most contentious aspects of the decision to award the tournament to Qatar, and estimates of the casualties have varied wildly.

A report by the Guardian newspaper last year said 6,500 migrant workers had died in Qatar since the Gulf state was awarded the World Cup in 2010 – something that had been "categorically" denied by authorities.

Speaking to TalkTV, Al-Thawadi said there had been three work-related deaths in construction directly for the tournament and 37 non work-related deaths, but that increased to 400-500 taking in all the infrastructure projects needed to support the hosting of the event.

Al-Thawadi said: "The estimate is around 400, between 400 and 500… I don't have the exact number. That’s something that’s been discussed."

He added: "One death is a death too many, plain and simple. I think every year the health and safety standards on the sites are improving, at least on the World Cup sites, the ones that we’re responsible for.

"To the extent that you’ve got trade unions – representatives of the German trade union, the Swiss trade union have commended the work that’s been done on the World Cup sites and the improvement.

"Improvements had to happen. This was something that was recognised before we bid.

"The improvements that have happened aren’t because of the World Cup, these are improvements that we knew we had to do because of our own values, whether it’s