The final stages of the UAE Tour were cancelled early on Friday after two team members tested positive for coronavirus.
Abu Dhabi Sports Council said two Italian participants were confirmed to have Covid-19. The Department of Health in Abu Dhabi later said it had taken precautionary measures in two hotels on Yas Island, where cyclists and crew had been staying, to test anyone that may have come into contact with the patients.
As a result, two more people "presumed to be contacts of the two Italian nationals" were quarantined. Further screenings are under way at the hotels, as part of a medical investigation. The department said some people who may have come into contact with the infected patients have been house-quarantined and would under go periodic testing over the next two weeks.
The two new patients were admitted to hospital where they are being treated and closely monitored, the department said in a statement carried by news agency Wam.
Early on Saturday, a statement carried on Wam said that the department had confirmed that tests carried out on 167 of those quarantined had returned a negative result.
More test results were expected "in the next few hours", the department said.
A spokeswoman for W Hotel told BBC the hotel was on "temporary lockdown" and that no one was allowed to leave or enter the property until it was deemed safe to do so by authorities.
She said the hotel was rebooking guests arriving on Friday in its sister hotels nearby.
The Crowne Plaza was also closed to visitors on Friday.
To avoid any potential spread of the contagious virus, the UAE Tour was cancelled.
"The decision has been taken to ensure protection of all the race's participants," the council said, adding that "safety comes at the top of all priorities".
The Ministry of Health and Prevention said all race participants, administrative staff and organisers will be screened and quarantined.
Cyclists and team staff have stayed at hotels on Yas Island for the duration of the tour. Several riders, teams and sports journalists confirmed they were confined to their hotel pending test results.
The health ministry said all "necessary precautions [and] preventive measures are being taken, including check-ups and observation of people in contact with patients", Wam reported.
All ports and entry points to Abu Dhabi are being monitored using thermal scanners, the Department of Health in Abu Dhabi said. "Required medical check-ups are being performed, and early warning systems are activated to monitor any suspected cases," it said.
Four-time Tour de France winner Chris Froome, who used the UAE Tour as a comeback after a serious accident last summer, said he was due to be tested.
"It's a shame that the #UAETour has been cancelled but public health must come first," he wrote on Twitter.
"We are all awaiting testing and will remain at the hotel until further notice. I hope those affected make a speedy recovery and there aren’t any further cases."
Italy's Vini Zabu-KTM team said its riders had been tested already.
"Tomorrow morning we will know the results. It's gonna be a long night and we hope that everyone will come back home without any trouble," it said in a statement on Twitter.
In Italy, the virus has spread fast in recent days with health officials confirming 650 cases and 17 deaths as of late Thursday.
The cycling team expressed frustration at rumours and comments made on social media.
"Now is not the time to give fake news," Vini Zabu wrote.
The final two stages were Al Ruwais to Al Mirfa (158 km) on Saturday and Al Maryah Island to Abu Dhabi (127 km) on Sunday.
*This story has been amended since publication