Three workers have been killed and a number of other people injured following an "incident" at a Qatari military construction site, state media reported.
In a statement posted on the Qatar News Agency website late yesterday, the Gulf state's defence ministry said the incident at a construction site of the Qatari Armed Forces "resulted in the deaths of three workers, in addition to a number of injuries."
No details were given of how, when or where the incident took place.
The statement added however that the ministry "stressed its commitment to abide by the highest safety standards in all its facilities."
It is the largest known loss of life in a single incident involving labourers since 13 workers died in a fire at an accommodation camp in June 2013.
Working conditions for labourers in Qatar are under worldwide scrutiny -- and criticism -- since the country was controversially chosen as the football World Cup 2022 host.
There have been two deaths of World Cup workers announced in the past seven months.
One of them, Zac Cox, died in a fall at the renovated Khalifa Stadium in January, which will officially be opened this weekend, the first 2022 stadium to be unveiled.
Despite much criticism, Qatar has denied most allegations of ill-treatment of its migrant workforce -- which numbers more than two million -- and has said it has introduced large-scale labour reform in recent years.