By Horaci García and Nacho Doce

BARCELONA, Feb 7 (Reuters) - Barcelona's city hall said on Friday it would buy an apartment block known as 'Casa Orsola' to prevent the eviction of several tenants, including a teacher who has become a symbol of Spain's housing crisis and months of protests against over-tourism.

City hall, along with a social housing association Habitat 3 Foundation, was stepping in to buy the Art Nouveau building in downtown Barcelona for about 9 million euros ($9.35 million) from Lioness Investments, Mayor Jaume Collboni told reporters.

"No tenant will have to leave Casa Orsola and all apartments will be converted into social and affordable renting," Collboni said, adding that the price paid for the building was 30% below current market value.

Josep Torrent, 49, who has lived in Casa Orsola for more than two decades, was among tenants who were told their rental contracts would not be renewed after private investors Lioness Investments acquired the building in 2020 with plans to transform its apartments into short-term rentals for tourists.

His case epitomizes the housing crisis affecting large cities in Spain, where rental prices are soaring amid rising gentrification exacerbated by insufficient homebuilding and an explosion of short-term tourism rentals offered on platforms such as AirBNB ABNB.O.

His eviction, approved by a court ruling, had been postponed several times following protests against gentrification and over-tourism.

Housing defence group Catalan Tenants Union welcomed the fact that Casa Orsola's apartments would not become expensive short-term lets but said city hall had paid too much for the building.

Lioness Investment, which has not disclosed how much it paid for the building, did not immediately reply to a request for comment.

Collboni had already announced a ban on short-term tourism rentals from 2028, in a bid to reduce the pressure on Barcelona's stretched housing market.

($1 = 0.9629 euros)

(Writing by Inti Landauro and Emma Pinedo; Editing by Charlie Devereux, William Maclean)

((Inti.Landauro@thomsonreuters.com;))