"Their timekeeping was just a bit too perfect for it to be a coincidence," realtor Josef Hejibel told The Local on Wednesday.

He said the fact that the four men arrived bang on time for the showing – set up camp outside to holler – only to leave on schedule was just one of three factors that tipped him off to the possibility the men had been hired to show up.

The ragtag bunch was also "much nosier than usual (alcoholics)", Hejibel said, and a neighbour quickly told him she had never experienced anything like it in her decade in the apartment block.

"I thought 'What on earth is going on'," neighbour Eva Bowerstone told the Metro newspaper on Wednesday. "I thought someone had become the victim of a crime, but then I saw the alcoholics sitting there screaming and squealing like stuck pigs."

As more than 50 flathunters inspected the flat in Södermalm on the first viewing, with another 20 so showing up on the second day, the squeals were loud enough to be heard inside the apartment – "the balcony door was open" – but not so noisy that Hejibel couldn't talk to the prospective bidders.

"I told all of them that I thought it was staged and most seemed to accept that," he said.

"There's a lot of pressure on the (property) market right now with high numbers of people looking for a new home and very high prices," he added. "I can't say with 100 percent accuracy that it was staged, but I believe that it was a desperate measure to frighten off the other would-be bidders."