The lockdown began at midnight, with the country struggling to curb the spread of the coronavirus.
“Not following the regulations and measures put in place to limit the spread of the virus is unacceptable,” Martin Hewitt, chair of the National Police Chiefs’ Council, said in the statement.
“We won’t waste time with endless encouragement for those who knowingly or deliberately break the rules.
“People recklessly ignoring the regulations should expect to receive a fixed penalty notice,” Hewitt added.
He said a minority of people had ignored the rules throughout the pandemic, but assured that police would “continue to engage with people proportionately, fairly and with common sense."
Total case count: The UK has recorded more than 1.1 million coronavirus cases and 47,000 virus-related deaths so far, according to a tally by Johns Hopkins University. It has the fifth-highest number of deaths in the world.