People who came into contact with builders on a site that was forced to close due to a Covid-19 outbreak are being urged to get tested as soon as poss- ible to prevent the virus from spreading further.
More than 20 employees on a building site in Dublin city centre have contracted the disease to date, it has been confirmed.
Up to 200 people were working on the site, which was temporarily closed by the Health Service Executive (HSE) yesterday.
Further tests on staff are being carried out.
John Paul Construction, which has offices in Dublin, Galway, Cork, London and Riyadh, confirmed a number of its building workers had contracted the virus.
There are fears over the infection rate due to the large number of people on the Townsend Street site, which is being developed for a 393-bedroom hotel, a 202-unit aparthotel, a restaurant and 21 apartments.
Acting Chief Medical Officer Dr Ronan Glynn described it as "the first significant outbreak" on a construction site.
It is understood one employee was initially diagnosed with Covid-19 at the end of last week.
Comprehensive testing was carried out once the company became aware of the case, and a number of other staff have since tested positive.
Labour councillor Kevin Donoghue described the outbreak as "very concerning".
He has called for testing to be made available for residents and shop workers in the area who may have come in contact with the staff.
"The workers on the site would have been using shops locally during breaks and we need to be ready to test local residents who might be impacted by this," Mr Donoghue said.
"Measures should be put in place to allow all residents in the area who are concerned to get tested immediately.
"In their statement, the construction company involved said comprehensive testing of workers had been carried out after one person tested positive for the virus.
"We need to ensure that testing is made available for locals also, especially where they may be concerned about at-risk family members."
In a statement, John Paul Construction confirmed that there had been a number of additional positive cases.
"Following confirmation that a staff member on one of our construction sites in Dublin had tested positive for Covid-19, testing has identified a number of additional positive cases," the company said.
"We have followed the spec- ific advice of the HSE and the Health and Safety Authority at all times in relation to this matter and are assisting the HSE in arranging further tests as required. We have temporarily closed the site.
"The health, safety and wellbeing of those who work with us and the communities in which we operate is our top priority and we wish those affected a speedy recovery."
The situation has been described as "fluid", and staff are due to be retested next week.
A spokesperson for the Health and Safety Authority (HSA) said: "We don't comment on specific enforcement activity or individual workplaces."
The HSE said it cannot comment on outbreaks, to protect the privacy and confidentiality of the businesses and the people who work in these facilities.
John Paul Construction has carried out a number of prominent construction projects involving Irish hotels including Adare Manor in Limerick and the Morgan in Dublin.
The construction industry has been hit hard by the coronavirus pandemic, and there are fears that employment will be significantly impacted in the coming months.
According to Construction Information Services (CIS), €17.9bn in project work was halted in Ireland as a res-ult of the Covid-19 industry shutdown.