The local infrastructure umbrella body Navca has warned that proposed changes to the laws governing trade unions would "further create an atmosphere in which campaigning and dissent is discouraged", particularly for civil society organisations.
Navca has responded to three consultations run by the Department for Business, Innovation and Skills on the trade union bill, which is going through parliament.
The consultations considered issues including the proposal to introduce a minimum level of participation of 50 per cent in ballots on industrial action and the use of agency staff during industrial action.
Navca’s response to the consultations, which closed yesterday, says that unions and staff associations are an essential part of civil society and in recent years there have been "increasing attacks on the right of civil society organisations to campaign".
It says: "We are concerned that this bill will continue the trend of the state attempting to restrict legitimate protest and will further create an atmosphere where campaigning and dissent is discouraged.
"We believe that citizens should be supported and encouraged to campaign as a way to hold the executive to account, prevent bad law-making and improve government."
It says the bill "goes against the democratic traditions of our society and in doing so challenges them".
The response says that the proposed thresholds for turnout are "alien to British culture".
It says: "Civil society groups, including charities, pride themselves on representing the people they exist to help. Democratic elections and votes are key to this, and although in committee meetings quorums are common-place, thresholds for elections are unheard of.
"This bill goes against the democratic traditions of our society and in doing so challenges them."
It also says there is a perception that the measures are politically motivated.
"Whether this perception is accurate or not it does create an unfortunate impression that the government is using its legislative power to silence dissenting voices."
The trade union bill is due to be debated in parliament next week.