The men believe their union activities are being used against them by firms involved in the Rock Triangle project in Bury, Greater Manchester.
They were among 3,213 workers named on an illegal database which was exposed in court last month.
Laing O'Rourke, main contractor at the site, has denied the claims.
A spokesman told the BBC: "We do not discriminate against any individuals for any reason in their employment and that is the clear policy across all our business units."
O'Rourke was one of more than 40 contractors which paid for access to the database of 3,213 workers run by businessman Ian Kerr, the Information Commissioner's Office (ICO) said.ADVERTISEMENT
He was fined ВЈ5,000 at Knutsford Crown Court in July after pleading guilty in May to breaching the Data Protection Act.
The database included names, dates of birth, national insurance numbers and details of whether an individual had any connection to trade union activity.
Its operation was suspended under the data protection laws and further regulations to outlaw such secret blacklists are to be introduced later in 2009.
But local workers protesting outside the Rock Triangle project on Thursday claimed they had been denied work on the site because of their appearance on the database.
The massive development, which covers 50,000 square metres, will bring shops, restaurants and 400 apartments to the town and is due to open next summer.
Colin Trousedale, from Bury, has 35 years experience in the electrical contracting industry but has been refused a job on the site.
"It's a local site to me. I would like employment on the site and I'm being blatantly refused. I feel it is by virtue of the fact I am on the blacklist," he said.
"Because of my past as a trade union representative I am persona non grata on these sites. They just won't allow me on the sites.
"How do I feed my family? How do I pay my bills? I can't. I'm on benefits by virtue of the fact I've stood up and said this is wrong."
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