Clashes erupt in Barcelona after thousands join Spain general strike

She was in the area of Las Ramblas in the evening and saw fires in the streets. "The fires were everywhere, it was very intense," she said.

Earlier in the day there was major disruption around Madrid and Barcelona, with traffic halted on several main roads.

The interior ministry said dozens of people were arrested for a variety of incidents and Spanish reports said estate agencies had seen attacks on their offices.

"We've completely brought the city to a standstill," a protester in Madrid told Reuters news agency, adding there was widespread support for the general strike. "Everyone's out there, despite the rainy weather; everyone's out on the streets."

Another protester, 37-year-old teacher Olga Domingo, said she was protesting because "the housing situation is outrageous. The current cost of living compared to wages is completely unsustainable".

The strike was triggered by widespread protests over affordable housing and rising living costs, after the eviction of 87-year-old Maricarmen Abascal from a flat in Madrid where she had lived for seven decades. She died in hospital weeks later.

Rental prices in the capital have risen in recent years. The monthly cost of a 50 sq m apartment in Madrid was an average of €1,170 ($1,300; £1,000) in October, according to property portal Idealista, while Spain's average gross monthly salary is about €2,460.

That amounts to nearly half the average gross salary, well above the 30% level of affordability often recommended by housing experts and public institutions.

The conservative People's Party (PP), by contrast, has accused the government of attempting to weaponise the strike for electoral gain.

PP leader Alberto Núñez Feijóo called the general strike "nonsense", calling the unions "mafia" and "trash". Feijoo's party is leading in the polls and party spokesman Miguel Tellado accused the government of exploiting the strike to warn voters against allowing a right-wing government to be formed, which looks the most likely outcome of the 29 November election.

Sánchez told Spanish TV this week: "What is nonsense is to question the rights of workers to strike."

Among those taking part in the general strike was Gonzalo Álvarez, 27, who was visiting different picket lines in central Madrid.

Although he works in sales, he has been volunteering for a housing union that tries to protect tenants and makes them aware of their rights.

The eviction of Maricarmen Abascal at the end of September "was the little fire" that sparked this protest, he told the BBC.

Álvarez knew the 87-year-old, who had faced a tripling of her rent under new landlords, and says he was deeply upset by her treatment.

He rents a small, one-bedroom flat with his girlfriend, a dental hygienist, in the city's southern Arganzuela disrict. The couple pay €1,000 between them, which means each spends about half of their salary on housing, even before other bills.

"It's absolutely crazy… with the food, with the electricity, with the water, with gas."

He sees no way of getting on the property ladder: "You have to collect an insane amount of money to be able to buy a house. So with these salaries, it's impossible."

With current rent and purchase prices, he believes buying somewhere is "completely impossible".

However, the vice-president of the CEOE, Spanish biggest business association, Miguel Garrido, criticised the strike, complaining that businesses had little to do with the price of housing.

"This is not a strike for labour-related reasons, but rather for political ones, and it is closely linked to the early calling of elections," he said.

Demonstrations were planned for some of Spain's biggest cities later in the day and the scale of support will be widely viewed as an indicator of public discontent ahead of the election.

Another reliable indicator of support for strikes is the level of demand for electricity with Spain's industrial sector.

Power usage in Spain fell by 7.5% during the early hours of Wednesday, according to data from operator Red Eléctrica. During the last general strike 14 years ago, equivalent consumption was down by more than 15%.

Additional reporting by Gabriela Pomeroy