An Italian police union has objected to officers being given pink coronavirus masks, warning they do not go with their uniforms and "risk damaging the institution's image".

In a letter to the national chief of police, published online Thursday, the head of the SAP union urged action against what he called the "perplexing" choice of colour of the FFP2 masks.

Stefano Paoloni said police managers must "preserve the decorum of their officers, ensuring they are not ordered to carry out institutional activities with protective devices (masks) in a colour that is eccentric to the uniform and risks damaging the image of the institution".

He suggested other colours such as white, blue or black would be suitable, to go with a uniform that is largely blue.

In an accompanying note cited by the Italian media, the union said it had no particular issue with pink, but said officers' uniforms were regulated.

On Twitter, deputy infrastructures minister Teresa Bellanova said there was "nothing undignified about wearing a coloured mask".

"Respect for uniforms does not come from the colours, but from the comportment and way of working of the men and women who wear them."

The SAP -- which has about 20,000 members, or around one in five Italian police officers -- said the pink masks had been distributed to a number of units in the north of Italy and in Sicily.

Masks are required to be worn in all public places in Italy, including outside, to stem the spread of coronavirus, with the higher-grade FFP2 masks mandated on public transport.