A New Zealand man has died while working on the massive stadium build in Qatar for football's 2022 World Cup.

Zac Cox, 40, is thought to have died instantly when equipment failed and he fell from a catwalk at Doha's Khalifa Stadium, which is being renovated for the tournament.

An investigation has been launched into the tragedy, the second death in a matter of months, fuelling fresh controversy over preparations for the FIFA event.

Good friend Steve Wilson said Mr Cox, who was born in Christchurch, was a close friend of many people.

Mr Cox had great tragedy in his life when his wife, Betsy, died of breast cancer aged 30.