Nearly 1.5m archaeological objects uncovered by commercial companies in Northern Ireland have not been passed on to local museums, MLAs were told on 2 July 2012.
Michelle McIlveen, chairwoman of the culture committee, gave the figures during a debate on archaeological artefacts.
She said the motion had been brought because the current system was "not working" as these objects - which included pottery, metalwork, glass or human remains - were being held outside the museum sector.
"There is a lack of statutory and planning policy provisions which have failed to address issues around the ownership and long-time curation of archaeological artefacts and excavation records," she said
The objects therefore cannot be assessed for their historical value, or put on display.
"This is putting Northern Ireland's heritage at risk," Miss McIlveen added.
Miss McIlveen's DUP colleague, Brenda Hale, said she was concerned that there was no record of the 1.5m items, "what they are, who has them, or where they are stored".
Sinn Fein's Oliver McMullan said the problem was a lack of "proper accountability".
He explained current Northern Ireland legislation stated that any finds should be reported to the Ulster Museum, the Environment Agency or an officer in charge at a police station.
The SDLP's Karen McKevitt said she was "disappointed" to learn that since 1999, no planning-led archaeological objects had been taken into the care of the Ulster Museum and the Environment Agency.
Ulster Unionist Robin Swann said the motion showed the "dysfunctionality of joined-up government" as it had to be brought by two committees - environment and culture - and one minister would respond to the debate on behalf of two departments.
Environment Minister Alex Attwood said "a strategic shift in government" was needed.
He said he would be speaking to the archaeological companies involved.
"They are getting money from from developers to do archaeological work and it seems to me that there are some who are deploying better practice than others," he said.
The motion was passed on an oral vote.
The Civil Service (Special Advisers) Bill also passed its first stage.