Thousands of health workers marched in Madrid on Sunday in support of Spain's public health system, sorely put to the test by the coronavirus.

With Spain one of the European countries hardest hit by the pandemic, some protesters waved placards bearing slogans such as "100% public health" and "no more rubbish contracts".

Organisers said roughly 10,000 people answered the call to demonstrate by the "Marea Blanca" (white tide) group, which is determined to put pressure on regional authorities they say are starving the system of sufficient investment.

Nurse Lara Garcia told AFP TV she wanted to highlight a reliance on temporary workers as well as low wages.

"Forty, 45% of staff are temporary, the salaries are lower than in other autonomous regions," said Garcia, highlighting that people were leaving the profession in droves.

"The healthcare workers take care of the lives of other people for one month, three months... it's unbearable."

Another nurse, Leonor Vallejo, 67, focused her ire on a new 1,000-bed hospital.

"The new hospital is a total scam for Madrid and the Madrilenos," she said. "It's totally unnecessary, they did it to earn money with the construction companies, speculating. Madrid has enough hospital beds that could have been used."

Health workers say they fear the new establishment has hoovered up resources which needed to be allocated more widely, including on staff recruitment.

More than 44,000 people have died from the virus in Spain from more than 1.6 million cases.