Rice is Nigeria's staple food and it is a tradition for people to give bags of rice as a gift during the Christmas period.
About 2.5 tonnes of the "plastic" rice has been confiscated, and Nigeria's food safety agency has denied claims by the health minister that it has cleared the reported "plastic" rice.
A senior official at the National Agency For Food and Drugs (Nafdac) said the minister's Twitter statement "is not their position".
Health Minister Isaac Adewole had tweeted that tests by the agency which are still ongoing, have found "no evidence" of plastic material.
Lagos customs chief Haruna Mamudu said on Wednesday the fake rice was intended to be sold during the festive season but has not commented on the health minister's statement.
"We are not done with comprehensive tests. We are still in the laboratory. We haven't concluded analysis and it is not something we can conclude in two days."
"We are yet to conclude the chemical and biological analysis," he added.
Mr Adewole had said the agency would "release detailed findings to public as soon as it concludes investigations", adding that Nigerians should remain calm.
It is not clear where the 102 seized sacks of rice came from but rice made from plastic pellets was found in China last year.
Mr Mamudu had said the rice was very sticky after it was boiled and "only God knows what would have happened" if people ate it.
The Lagos customs chief had called on "economic saboteurs who see yuletide season as a peak period for their nefarious acts to desist from such illegal" business activity.
We haven't heard any reports that the rice is still on sale in markets. Customs officials were investigating but as of now have found nothing.
Nigeria's custom officials say they seized a total of 102 sacks, each containing 25kg (55lb), branded "Best Tomato Rice".
It is, however, unclear how many bags had been sold, if any, and if there are other forms of contraband in the market.
We haven't heard of any members of the public eating it.
Customs officials cooked the rice and said that the texture was very gummy and it smelled odd, they refused to eat it.
An unverified video of the rice being cooked has been shared on social media.
In it the cook says the rice catches fire and sticks on the pan.
Nigerians are very worried. There have been several media reports warning the public about fake foodstuffs especially from China and their potential dangers.
Speaking to the BBC's World Have Your Say programme Ibrahim, from Kano State, said selling fake rice was wickedness of the highest order.
- Countries: Africa