The North's Human Rights Commission should be able to question MI5 about alleged human rights abuses, the chief commissioner said today.
Monica McWilliams wants the power to examine possible wrongdoing by the British intelligence services.
Relatives of the 29 who died in the 1998 Omagh bomb have claimed MI5 failed to pass on information.
The Justice and Security Bill being considered in Westminster would exempt intelligence services MI5 and MI6 and national-security matters from scrutiny.
Ms McWilliams said: "It is a very wide-ranging exemption and it would put a lot of limitations on what we would be able to investigate and we are hoping it could be amended.
"We say we should have the power to investigate matters retrospectively.
"We hope to have these powers by January 2008 so it would be a number of years after that before there would be evidence and documents available."
Established under the Good Friday Agreement ending armed conflict in the North, the commission advocates human-rights protection in law, policy and practice.
Democratic Unionist leader Ian Paisley demanded Ms McWilliams' removal in the House of Commons this week and called for the commission to be "reined in".
The proposed exemptions would cover national security, including Police Service of Northern Ireland involvement.
MI5, which fights insurgency within the UK, and MI6, which works abroad, would both be exempt.
MI5 is building a centre near Holywood, Co Down, and is due to take over responsibility for national security from the police.
PSNI Chief Constable Hugh Orde said his force would not be sidelined in any matters involving the North.
The SDLP has pressed for Northern Police Ombudsman Nuala O'Loan to be allowed to hold MI5 to account.
MI5 was criticised amid allegations it failed to pass on warnings from an informer about the August 1998 Omagh bomb. Relatives of those killed are calling for an independent public inquiry into this and other matters of concern.
MI5 is already covered by surveillance and intercept commissioners as well as an Investigatory Powers Tribunal.
The tribunal has not upheld any complaints about actions in the North.
"We hope to secure retrospective powers but national security will be more difficult, given the atmosphere around international terrorism," Ms McWilliams said.
"We want to look at this in the context of Northern Ireland and the issue of covert surveillance and it is important that the intelligence services understand their human rights responsibilities."