Leinster have revealed that more positive Covid-19 cases have been reported in the latest round of testing.
The Irish province already had three senior players and a staff member ahead of last weekend's game and had postponed their training awaiting latest round of PCR test results.
"Leinster Rugby can confirm that the club is assisting an additional number of senior players who have tested positive for Covid-19 and are now self-isolating.
"The latest cases follow the antigen and PCR testing which were carried out at Leinster Rugby on all players, coaches and staff.
"The HSE has been informed in accordance with public health guidelines, as has EPCR.
"The remaining members of the Leinster Rugby squad will train today in UCD and will continue to test daily and take all necessary precautions ahead of Friday's Heineken Champions Cup game against Montpellier in France."
Leinster will be facing Montpellier in the second round of the competition with the French side already reporting their fifth positive Covid-19 case on Tuesday.
"Following the series of tests carried out on Monday, December 13, Montpellier Herault Rugby formalises a new positive case for Covid-19 within the group," read a statement from the Top14 side.
"This is the fifth case of contamination detected over a period of seven days in the Herault workforce, which considerably impacts the preparation for the match against Leinster Rugby scheduled for Friday, December 17.
"In view of the latest results, the people concerned have been isolated and the team is now carrying out training in separate groups before being tested again this Wednesday, December 15.
"The club remains mobilised by continuing to apply a strict and rigorous health policy in order to preserve the health of its players and staff."