Spain's health emergency chief said Tuesday he was sorry for a throwaway sexist comment that had outraged the national nurses' guild, prompting the government to demand that he apologise.

The controversy erupted on Friday after the emergence of an interview on YouTube with Fernando Simon, the public face of Spain's response to the pandemic who runs the health ministry's emergencies unit. 

During the interview, he was asked if he liked "infectious diseases or infectious nurses," to which he replied: "I didn't ask (the nurses) if they were infectious or not, you (only) see that a few days later."

The General Council of Nurses lashed out at Simon over his display of "chauvinist and backward disinhibition", denouncing his remarks as "sexist and primitive". 

"We nurses have for decades been fighting to get rid of all the chauvinistic images and stereotypes," the council said, adding it was "intolerable that a person in Simon's position could allow himself to denigrate" the profession during the pandemic.

But on Tuesday Simon apologised, saying it was "a very stupid joke" to which he had given "very improper response". 

"I want to apologise to everyone and any groups that were upset by my words which were said in jest. I am sorry," he said at the start of his daily virus news conference. 

"But the truth is.. I feel really bad that after all these years of trying to rid of these learned reflexes and ways of talking that have nothing to do with my way of thinking.. I still have a lot left to learn," he said. 

"I'll try not to make any more mistakes like this again."

Earlier on Tuesday, Deputy Prime Minister Carmen Calvo said Simon should apologise "as an individual, as a citizen and as a man" for his "very inappropriate" comment which "does not help boost equality and respect for women".

An epidemiologist who has worked in Latin America and in Africa for the European Union and the World Health Organization, Simon, 57, often uses an informal tone during the health ministry's daily televised briefings on the virus.

He has been criticised by Spain's right-wing opposition for not calling for more drastic measures at the start of the pandemic, which has now claimed more than 36,000 lives.

Simon himself caught Covid-19 in March, but continued to take part in the ministry's televised briefings from home.

His thick eyebrows and unruly mop of salt-and-pepper hair have been a gift to the nation's cartoonists.

In 2014, he led the response to the Ebola outbreak, when two Spanish missionaries died in a Madrid hospital of the deadly disease.

Spain's health emergency chief said Tuesday he was sorry for a throwaway sexist comment that had outraged the national nurses' guild, prompting the government to demand that he apologise.