MONTREAL- An $80,000 federal study into organized crime in the construction industry has been plagued by people's refusal to be interviewed.

Of the 35 organizations contacted by the study authors, only six responded by putting forward representatives willing to speak.

The study authors say they tried interviewing contractors, union representatives, provincial prosecutors and law-enforcement agencies.

Twenty-nine of the 35 institutions they contacted either refused the invitation to participate or simply did not respond to the request. The study authors managed to speak to 17 people from the other six organizations.

The final report, released under the Access to Information Act, indicates that some participants feared reprisals or being tainted by association, while others feared the study authors were covertly working for police.

Others were apparently worried about heavy media coverage given to the construction industry in Quebec over the last few years.

A barrage of reports about cost overruns in the construction industry, and its ties to crime groups like the Mafia, has prompted a public inquiry that will soon begin in Quebec.

Amid such controversy, the federal government commissioned a study into whether the construction industry in two provinces -- Quebec and British Columbia -- was vulnerable to criminal infiltration.

The study was commissioned in late 2010 by Public Safety Canada, at an announced cost of at least $80,000, and was delayed in part by developments in Quebec in late 2011. Late last year, Quebec announced plans to launch a construction inquiry headed by Superior Court Justice France Charbonneau.

The newly released federal study concludes that the Canadian commercial construction sector is at a moderate to high risk of corruption and organized crime.

"Research into organized crime and the commercial construction sector faces certain difficulties, some general and some specific to the current media exposure this issue has received, especially in the province of Quebec," said the report, authored by seven academics.

"The challenges we have faced have been encountered by others undertaking research on organized crime," it added, citing similar woes that undermined research done at Tilburg University in the Netherlands.