Expo 2020 Dubai, a major world fair that opened last week, on Sunday said three workers on the project had died after contracting Covid-19, revising up the total number of worker fatalities since 2015 to six.
The organiser had for the first time on Saturday disclosed three work-related deaths and 72 serious injuries among 200,000 workers during construction of the site, defending the accident rate as less than half of that of building work in Britain.
"Unfortunately we had three worker related deaths due to Covid. That was during the course of the pandemic," Expo representative Sconaid McGeachin told a daily briefing.
McGeachin said the three deaths disclosed earlier were construction-related. She referred reporters to local authorities for comment on how many Expo workers had so far caught Covid-19.
The Dubai government media office did not immediately respond to an emailed Reuters request for comment.
Huge projects in the Gulf region such as the Expo, and Qatar's preparations for hosting the 2022 FIFA soccer World Cup, have faced international scrutiny, with rights groups criticising conditions for low-paid migrant workers.
Overcrowding in worker accommodation was one of the main factors in a surge of infections in the United Arab Emirates and other Gulf states at the start of the pandemic.
There are limited protections in the UAE and other Gulf states for migrant workers. Those in blue collar jobs, who work long hours and are paid low salaries, are the most vulnerable. Unlawful practices by employers and recruiters are common such as illegally charging blue collar workers agency and visa fees.
Expo 2020 says it enforces higher workplace standards than UAE law requires and that it audits contractors for adherence and intervenes when infringements are found.
It has not released detailed information on violations.
The UAE does not give a breakdown for Covid-19 cases and deaths for each emirate, including regional trade and tourism hub Dubai. The country has rolled out one of the world's fastest vaccination campaigns, with more than 80% of the population of some 10 million people inoculated.
The UAE is betting the six-month Expo will attract 25 million visits. Visitors entering aged 18 and over must show proof of vaccination or a negative Covid-19 test. There are also testing facilities on site.