Home heating oil in Northern Ireland was described as "a massive unregulated industry" by a Sinn Fein MLA on 6 February 2012.
Phil Flanagan said much greater transparency was needed within the market.
He was speaking on a Sinn Fein motion which called on the enterprise minister to introduce regulation to the industry.
Mr Flanagan said regulation could create an initial additional cost to consumers but he claimed these would be outweighed by the long-term benefits it would provide.
Trevor Lunn of the Alliance Party proposed an amendment to the motion which acknowledged an "over-reliance on our unregulated home heating oil market".
His amendment did not call for regulation but instead urged the minister to further engage with the Office of Fair Trading, the Consumer Council and the Utility Regulator.
Mr Lunn said he could not support the original motion as it was "frankly unrealistic".
UUP and DUP speakers expressed support for the Alliance Party's amendment, whereas the Green Party and the SDLP supported the original motion.
Responding to the debate, Enterprise Minister Arlene Foster said her department did not have a statutory remit for the Northern Ireland supply chain and said any regulation of the industry would be "a significant departure of policy, not just from the rest of the UK, but also the Republic of Ireland and most EU countries".
She said the supply operated in a "highly competitive global market under national and EU laws".
Mrs Foster added that the UK's open market was regulated by the Office of Fair Trading and the competition commission and there were measures in place to ensure prices were fair.
The amended motion was passed.