Nationalists have warned the British government that they will oppose any attempt to introduce 'draconian' new laws allowing a British Direct Ruler to order that inquests must be held in secret.
Last month the "Counter-Terrorism Bill 2008" passed its second reading in the London parliament.
Among the more controversial pieces of legislation included is the proposal to allow the British government to stop inquests from being held in public.
Under the new laws, a a Direct Ruler in the North of Ireland would be allowed to dismiss both juries and coroners from inquests if it is judged to be in the public interest, against British state security or would damage relationships with another country.
While the British government insists that the inquest powers would not be used in the Six Counties, there are concerns that it could be used to block a series of highly controversial 'shoot to kill' inquests which are due to open in the north next year.
In 2005 the British government rushed through legislation allowing it to withhold sensitive material from an inquiry set up to investigate Crown force collusion in the 1989 murder of Belfast defence lawyer Pat Finucane.
Since then the act has been extended to restrict evidence being heard by inquiries into the killings of Robert Hamill and Billy Wright.
Warning that his party would oppose any attempt to block inquests, Sinn Féin assembly member Alex Maskey said: "It has been shown time and time again that the British government will use anything in its powers to block public inquiries and inquests from getting to the truth.
"I have no doubt that the British government will try to use this draconian legislation to help cover-up the collusion that has gone on in the north for the last 40 years."
Rejecting government assurances that the new powers would not be extended to Northern Ireland, SDLP leader Mark Durkan said: "There is a completely new provision in this legislation.
"It's not confined to terrorist cases, whereby the secretary of state will be able to appoint a special coroner to hold a secret inquest in relation to any death where they think that's in the public interest.
"If they get it through in this bill, they will very quickly then extend it to Northern Ireland.
"That has huge implications for the outstanding cases in Northern Ireland in which there have never been inquests held."