Denmark’s ban against the use of full-face veils in public spaces, called a “burqa ban,” went into effect on Wednesday.
The Danish parliament approved the ban in May.
It includes full-face veils like the niqab, balaclavas, face-covering ski masks, face masks and fake beards, but not protective masks.
A first-time offender could risk a fine of 1,000 kroner (156 dollars). Repeat offences would result in a higher fine.
A fourth offence and any further violations would be met with a fine of 10,000 kroner.
Protests against the ban were planned later on Wednesday in the capital Copenhagen and the city of Aarhus.
Police said protesters who planned to fully cover their faces at the demonstrations would not risk a fine.
“The demonstrations were considered part of freedom of expression and freedom of assembly,” Benny Ochkenholt of the Danish national police told public broadcaster DR.
Fines could, however, be issued if participants were masked on their way to or from the demonstrations, he added.
Exemptions to the ban include winter clothing, such as scarves, and costumes and masks worn for carnival or Halloween.
Danish police federation president Claus Oxfeldt said the guidelines were not sufficiently detailed.
The police federation and national police were to meet in September to assess the first month of the ban, he told news agency Ritzau.
Some countries in Europe, including Austria, Belgium and France, have previously introduced restrictions on wearing full-face veils in public spaces.
A 2010 report estimated that up to 200 women in Denmark, a country of 5.7 million, used full-face veils.