Forty-nine Vatican Museums employees have started an unprecedented labour dispute over what they say are unfair and poor conditions at their workplace, which could lead to an embarrassing lawsuit against Pope Francis' administration.

The workers, mostly museum attendants, have sent a petition to the Vatican's "Governatorato", the body that administers the Vatican City State, lamenting rules that cause "labour conditions undermining each worker's dignity and health", said lawyer Laura Sgrò, who is representing them.

They include extra work hours paid at lower rates and insufficient health and safety provisions, Sgrò said.

"Workers have decided this action only after all their demands and requests over years were left unanswered," she said.

Unions are not allowed in Vatican City.

A spokesman for the Vatican Museums declined to comment.

The news was initially reported on Sunday by the Il Corriere della Sera daily.

The 49 workers, out of a total of around 700 people employed at the Vatican Museums, are all Italian citizens and have been employed at the Vatican for many years.

One of the most visited museums in the world, along with Paris' Louvre and London's British Museum, the Vatican Museums have a priceless art collection and include the renowned Michelangelo's Sistine Chapel.

The petition represents the first formal step in a mandatory conciliation process under Vatican law.

If the conciliation procedure fails, the case can then be brought to a Vatican Court.

Sgrò added that, due to the absence of furlough schemes in Vatican labour legislation, workers who had been left inactive during the COVID-19 pandemic because of the Vatican Museums' closure were now being asked to hand back salaries paid during that period.

"With this action we want to be constructive, we hope this can prove the right occasion for a general rethinking of the Vatican labour rules," Sgrò said.