The Secretary General of the Dept of Agriculture says he cannot comment on the type of oil found in feed given to pigs before the pork withdrawal in December.
Tom Moran told the Oireachtas Committee on Agriculture that as this was still being investigated, he could not comment.
He did say the dioxin problem had started not in the animal feed, but in oil used to dry the feed.
Mr Moran also confirmed that Christmas sales of Irish pork products in Ireland were strong despite the withdrawal.
However, problems remain in some export markets.
Bord Bia said its not clear yet what impact the withdrawal of pig meat has had on sales and exports of Irish pork products. The Government has set up a contingency fund of nearly €200m to compensate processors and farmers.
Pork recall
The Oireachtas committee is investigating how the dioxin contamination crisis was handled.
Last month, pork products had to be withdrawn from butchers and supermarket shelves after the discovery of dioxin contamination, which was traced to animal feed from a recycling plant in Co Carlow.
The investigating committee into the contamination is made up TDs and Senators.
They are examining the proportionality of the response by the authorities to the crisis, the effectiveness of food traceability and the procedures for monitoring licensed premises that manufacture animal feed.
Department of Agriculture Secretary General Tom Moran and the State's chief veterinary officer, Paddy Rogan, appeared this morning.
Committee chairman Deputy Johnny Brady said the politicians were there to question people who made key decisions during the incident and discuss what lessons might be learned.
