The Canada-Newfoundland and Labrador Offshore Petroleum Board says 3,000 litres of methanol was leaked into the ocean from Suncor's subsea drill centre in the Terra Nova field on Wednesday.
In a release, the C-NLOPB said production was stopped once the leak was detected.
The board is reviewing the incident and Suncor is investigating.
Suncor added that the oil platform southeast of Newfoundland entered "alarm status" Thursday after a small flame was detected.
The company was alerted to the incident when a small flame became visible on the insulation blanket for "the lower medium pressure turret swivel due to the creation of an arc in an electrical circuit."
The flame was extinguished, and the circuit, Suncor said, was isolated.
No injuries were reported.
According to Suncor, the platform is one of the largest floating production storage and offloading vessels ever built.
It stands more than 18 storeys high and spans the length of approximately three football fields.
The vessel can store 960,000 barrels of oil and can hold up to 120 personnel while in operation.