Super League newcomers Toronto Wolfpack have suspended training and stood down their entire UK-based staff after four players experienced symptoms of coronavirus.
The Canadian club's decision means their next fixture against Wakefield next Sunday will almost certainly be postponed. It may signal a shutdown of the league.
The identity of the players is not known.
"We have advised four of our players who have experienced mild possible symptoms of COVID-19 to self-isolate in accordance with the guidelines set by the UK government," Wolfpack coach Brian McDermott said in a statement.
"We take this very seriously and as a precaution, we have stood down our entire playing staff in the UK."
The Wolfpack, whose squad includes Sonny Bill Williams, use Hopwood Hall College as their training base in England.
"We train in an environment where we interact with students and members of the public and we vehemently do not want to act as a possible vector for COVID-19 which is why we have taken this immediate action," McDermott said.
We have stood down our entire playing staff in the UK
Wolfpack coach Brian McDermott
"The health and welfare of our players, staff, fans and partners is always our primary concern.
"Our main goal is to prevent any further spread to our playing squad and their immediate family members, therefore we are now postponing all practice and have tasked our squad with keeping themselves healthy.
"We will continue to monitor this while providing updates to our League’s governors and wait for a directive from them."