Hundreds of activists delayed the opening of an international real estate fair in the northeastern Spanish city of Barcelona on Wednesday as they protested against what they called a hotbed of speculation exacerbating a widening cost of living crisis.

Dozens burst into the fairgrounds, chanting slogans and preventing the opening ceremony from taking place before being removed by police. Others gathered outside the building, where they lobbed paint at some of the arriving attendees, Reuters journalists said. Police in riot gear stood at the entrance.

Housing rights groups had called for a boycott of the fair, named The District World Summit 2022, in a joint manifesto that blamed local authorities, banks and investment funds for the city's gentrification and soaring rents.

"In a city punished by the economic context, where every day there are over 20 evictions, we have learned that the main promoters of the majority of the population's misery will meet in Barcelona to continue developing strategies to exploit the territory and resources, speculate and deepen the processes of impoverishment and social expulsion," they said.

The activists held up a banner that read "Let's defend life, let's stop The District" and "Speculators, get out of our neighbourhoods".

More than 1,200 investors are expected to attend the fair, which features over 380 speakers from companies such as U.S. asset manager Blackstone or private equity firm TPG , organisers said.

Average rent prices in Spain's second-largest city of over 1.6 million people surged to an all-time high of 17.8 euros ($17.47) per square meter in September, a 20.3% year-on-year increase far outpacing Spain's 12-month inflation of 8.9%, data from real estate portal Idealista.com showed.

($1 = 1.0186 euros) (Reporting by Nacho Doce; Writing by David Latona; Editing by Andrei Khalip and Angus MacSwan)