BUDAPEST, Hungary— Health officials in Hungary on Thursday reported more than 8,300 new COVID-19 cases, the highest single-day total since the beginning of the pandemic.

Officials say the increase in new infections is likely due to a variant of the virus first discovered in Britain, which has led to a sharp surge in new cases, hospitalizations and deaths.

Hungary has more patients being treated in hospitals now than at any other time during the pandemic, putting a strain on its understaffed healthcare system. Doctors at several hospitals say intensive wards are filling up, and that they are having to give priority to younger critical patients with higher chances of survival when determining who to admit to intensive care.

A new round of lockdown restrictions were introduced on Monday to curb the surge, including mandatory closure of most businesses and suspension of kindergartens and primary schools.

As of Thursday, 16,497 coronavirus-related deaths were confirmed in the country of fewer than 10 million.