China has admitted that six workers have been killed on Olympic Games construction projects since 2003.
Two of the six deaths occurred at main Olympic venue, said officials
Until now, Beijing had denied there had been any fatalities on the building sites being readied for this August's Games.
Officials said the families of the dead workers had been compensated.
Games organisers last week dismissed a report in a British newspaper that at least 10 workers had died building the main Olympic venue.
Officials now say two workers died at the National Stadium in Beijing.
Ding Zhenkuan, deputy chief of the Chinese capital's Municipal Bureau of Work Safety, said they were among six workers who had died over five years.
There was also one serious injury and three lighter injuries, he added.
Problems were noticed as the main swimming venue was unveiled
The Sunday Times reported that the authorities had tried to cover up the deaths of 10 workers at the 90,000-seat main venue, which is also known as the "birds' nest".
China's work safety record is poor - more than 100,000 people die every year in workplace incidents.
The admission came as Beijing unveiled the venue for the Games swimming and diving events.
The BBC's Daniel Griffiths discovered some problems at the opening ceremony of the National Aquatic Centre.
He noticed cracks running along the length of two of the diving platforms.
Officials told reporters everything would be fixed before the event began.
Since construction began in 2003, organisers have built or refurbished 37 venues for the Games, 31 of them in Beijing.