World Cup host Qatar has failed to investigate the deaths of thousands of migrant workers in the past decade, according to a new report by Amnesty International.

The human rights organisation said the majority of migrant worker deaths in Qatar are attributed to “natural causes”, cardiac or respiratory failure; classifications which are “meaningless” without the underlying cause of death explained, according to one expert cited.

As a result, as many as 70% of deaths may be unexplained. “In a well resourced health system, it should be possible to identify the exact cause of death in all but 1% of cases,” the report said.