Contract Journal understands that the new regulations are due to be published as a Statutory Instrument within the next few days.
The process means there will be limited or no debate in Parliament and the regulations will go through automatically.
One campaigner said: "This could be our last change to get the legislation strengthened and we are urging everyone to get in touch with their MPs and ask them to put pressure on Peter Mandelson who is behind this move.
"Mandelson said he would stamp out blacklisting but the plans don't go far enough.ADVERTISEMENT
"They don't make it a criminal offence and fail to uphold workers' human rights under European charters.
"They don't give workers the right not to be blacklisted and only cover blacklisting for trade union activities.
"These regulations need to go further so we need people to take action now before everything is just nodded through Parliament."
Mandelson launched a consultation on new blacklisting regulations in the wake of the Consulting Association scandal which saw a blacklist held on thousands of construction workers.
He said: "Blacklisting someone because they are a member of a trade union is totally unacceptable.
"I am determined to act quickly to stamp out this despicable practice."
The planned proposals make it:
unlawful for organisations to refuse employment or sack individuals as a result of appearing on a blacklist
unlawful for employment agencies to refuse to provide a service on the basis of appearing on a blacklist and
enable individuals or unions to pursue compensation or solicit action against those who compile, distribute or use blacklists.
Prison call for blacklistersWorkers’ fears hinder unions