Italian police have protested to the interior ministry after being sent pink health masks to wear on duty, saying the color risked damaging their reputation.

"We do not understand the reason behind the purchase of masks in a color that would appear at first sight to be unsuitable for our administration," the police union wrote in a letter to the interior ministry.

"This purchase is puzzling," the letter said, adding that two years into the COVID-19 health crisis it should be easy to purchase appropriate face masks.

In future, masks should only be black, white or blue, they said.

There was no immediate comment from the interior ministry.