Montpellier have reported a fifth positive Covid-19 test ahead of Friday's scheduled Heineken Champions Cup game against Leinster in France.
It comes after Leinster postponed training on Monday prior to their latest PCR testing results, with the Irish province announcing last week that three senior players and one member of staff had tested positive for Covid-19.
Friday's pool-stage opponents Montpellier have now announced a fifth positive test in the space of a week, isolating those concerned and splitting the team into separate groups for training.
"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 posted on the club's official website.
"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."
Montpellier opened their European Cup campaign with a 42-6 defeat against Exeter Chiefs last weekend, while Leinster defeated Bath 45-20.
Leinster planned a full round of testing on Monday, with training postponed as a precautionary measure until all results are confirmed.