(Adds details on British Columbia's new saline mouth rinse testing program)
By Allison Martell and David Ljunggren
TORONTO/OTTAWA, Sept 17 (Reuters) - Canada's most populous province will clamp down on social gatherings to prevent "reckless careless people" from spreading the coronavirus at illegal parties, Ontario Premier Doug Ford said on Thursday.
His warning came as the nation's top medical officer said authorities could potentially lose the ability to manage the pandemic.
Starting Friday, indoor social events in Toronto, Canada's biggest city - along with Ontario's Peel and Ottawa regions - would be authorized to include no more than 10 people from a previous limit of 50, Ford said.
The cap on outdoor gatherings would shrink to 25 from 100, he added, saying anyone breaking the law would face fines of up to C$10,000 ($7,580).
"This is a serious situation, folks. We will throw the book at you if you break the rules," he told a news conference, saying people were "drinking, hugging, kissing, spitting ... (and) spreading COVID-19" at illegal parties.
Canada's chief Public Health Officer Theresa Tam said an average of 779 new cases had been reported daily during the most recent week, more than double the level in July.
The pandemic has killed more than 9,000 Canadians and authorities are on high alert to prevent a second wave.
Tam cautioned that continued circulation of the virus could change the situation. "We could lose the ability to keep COVID-19 cases at manageable levels," she said.
In London, Ontario, Western University posted on Twitter it had halted many non-academic activities on campus after 28 students tested positive.
An increase in cases, combined with school rules that require tests for most children or parents with mild symptoms, have driven tens of thousands to testing centers, where many have had to wait hours to be seen.
British Columbia, Canada's westernmost province, announced a new program for children ages 4 to 19 to collect a sample via saline mouth rinse to use for COVID-19 tests, instead of the nasal swab test that a nurse performs.
Dr. Bonnie Henry, British Columbia's provincial health officer, described the program as one of the first of its kind in the world that would make testing easier as schools reopen.
($1 = 1.3191 Canadian dollars)