Faced with searing heat, no air conditioning and a ban on wearing shorts to work, a male civil servant in Rio swapped his trousers for his wife's skirt.

Andre Amaral Silva, 41, decided to take sartorial action as the thermometer Tuesday hit 40.8 (105.4 Fahrenheit) and picked out a long black skirt from his wife's wardrobe.

He then sent up the picture to Facebook, whereupon some 5,000 people shared it within hours and by Wednesday Silva was in the newspapers.

The draftsman said the caretaker of the building where he works had tried to prevent him entering dressed as he was.

He retorted that "if women are allowed (to wear a skirt) then I am too."

Even then, it took an administrator to confirm that "wearing a skirt is permitted."

Silva told O Globo daily: "It was all resolved very easily. People end up obeying rules without knowing where they come from.

"We are without air conditioning and even in this heat it hasn't been repaired," he explained.

Silva added the skirt proved so comfortable he is thinking of not giving it back to his wife.

The head of the Rio judiciary, Leila Mariana, last month ruled that lawyers on duty in Rio state need not swelter in full regalia given the excessive heat.

But shorts were banned and long trousers and long-sleeved shirts remain de rigueur as do full suit and tie for when courts are in session.