“There is cause to suspect that several people have accepted perks which can be classified as bribes,” said Nils-Erik Schultz at the National Anti-Corruption Unit (Riksenheten mot korruption) to news agency TT.

The investigation concerns the Gothenburg municipal housing firm Familjebostäder and the city’s sports and clubs division.

Officials from the two organisations had difficulty explaining their relationship with the contractor Stefan Allbäck when approached by Sveriges Television’s Uppdrag Granskning programme, which also claimed that several of the invoices submitted for public projects, and approved by the municipal officials concerned, contained gross irregularities.

“There were a number of facts and allegations which permit one to assume and suspect that some people have received benefits that could be classified as bribes. But it is difficult to single out a particular detail in the programme,” said Schultz by way of explanation for why he had opened the investigation.

When SVT approached Stefan Allbäck over the allegations against him he initially threatened to sue the programme for defamation, which he claimed has victimized him since 2005. Allbäck explained that a police investigation was ongoing and declined to comment further.

Many of the accusations forwarded to the municipality that Allbäck referred to came from the ex-wife of one of the officials implicated, and whose allegations formed the basis of Uppdrag Granskning’s report. Despite having provided a wealth of supporting evidence the municipality had previously declined to open an investigation into her allegations of bribery and corruption involving her ex-husband and Allbäck.

According to SVT sources, cited anonymously in the programme, in return for carrying out various private construction jobs for municipal officials, Allbäck secured contracts for various public projects, which were then charged to the municipality at a cost in excess of their value.

Further accusations were leveled at the officials for accepting paid holidays to the French Riviera, luxury restaurant visits and car repairs – all paid for by Stefan Allbäck.

There are currently no suspects in the case, which could be extended to cover both the receipt (mutbrott) and the giving of bribes (bestickning).

“Not yet. We are looking at possible bribery offences, then we’ll see where it leads,” said Schultz, who will arrive in Gothenburg on Tuesday to open the investigation.

The SVT programme shows that when presented with details of apparent irregularities over inflated invoices and work charged for but never delivered, officials at the city’s sports and clubs division declined to comment.

Senior politicians in Gothenburg have responded to the allegations in the SVT programme by promising to get to the bottom of the “you scratch my back, I’ll scratch yours buddy culture” which appears to have developed between officials employed within the municipality and publicly-owned firms and Stefan Allbäck.

On Thursday, the day after the programme aired, Anneli Hulthén, chairperson of the Gothenburg Municipality’s executive board, called a meeting of all the municipal housing companies to discuss the allegations.

“I want to know if there are rumours over similar incidents in one of our other municipal housing companies. What are the control systems in place? Can we learn from each other? Familjeböstäder now claims that this could never happen today as they have new routines in place,” said Anneli Hulthén to TT.