LONDON -- Thousands gathered Saturday at London's Trafalgar Square to protest lockdowns and social distancing rules imposed to slow the spread of COVID-19.

London's Metropolitan Police has warned demonstrators to follow social-distancing rules. Police said before the event that officers will first engage with people and explain the social distancing rules, but they may take enforcement action if protesters still fail to comply. As the protest began, police were visible around the edges of the crowd but didn't confront protesters, most of whom weren't wearing masks.

"I know there is great frustration to these regulations, but they have been designed to keep everyone safe from what is a lethal virus," Cmdr. Ade Adelekan said. "By flagrantly gathering in large numbers and ignoring social distancing, you are putting your health and the health of your loved ones at risk."

The demonstration comes as Parliament prepares to review COVID-19 legislation and the government imposes new restrictions to control the disease. Some lawmakers have criticized the government for implementing the rules without parliamentary approval.

Speakers at the rally denied they were conspiracy theorists, arguing they were standing up for freedom of expression and human rights.

Dan Astin-Gregory, a leadership trainer, acknowledged the deaths and suffering caused by the pandemic, but said the response to COVID-19 has been out of proportion to the threat caused by the disease.

"We are tired of the fear mongering and the misrepresentation of the facts," he told the crowd. "We are tired of the restrictions to our freedoms."

The government earlier this week ordered a 10 p.m. curfew on bars and restaurants nationwide, along with tougher facemask requirements and increased fines for non-compliance. It has also banned most social gatherings of more than six people, but there is an exemption for protests as long as organizers submit a risk assessment and comply with social distancing.

The demonstration comes a week after a similar event during which thousands of people crowded into the iconic square. Police say several officers were hurt during that event when a "small minority" of protesters became violent.

Britain has Europe's worst death toll from the pandemic, with nearly 42,000 confirmed deaths tied to COVID-19. New infections, hospitalizations and deaths have all risen sharply in recent weeks.

In addition to the nationwide COVID-19 rules, several jurisdictions have imposed tighter restrictions to control local spikes in the disease. By Monday, one-quarter of the U.K.'s 65 million people will be living under these heightened restrictions.

London, home to almost 9 million people, on Friday was added to the British government's COVID-19 watchlist as an "area of concern." That means the U.K. capital could face new restrictions as well, if infections continue to rise in the city.