Company spokesperson Sneh Seetal says about 225 barrels of a soybean-based biodegradable biodiesel blending agent leaked from a storage tank on Saturday.
The company immediately activated its response plan, blocking storm sewers, setting up booms and reporting the spill to the federal and provincial environment ministries.
Most the spill was captured in a trench, but about two litres spilled into the Burrard Inlet.
The public was not notified, and the incident only came to light after local media reported it.
Seetal says she understands the lack of public notification may have raised concerns.
"When the public is worried and concerned, we are as well, and that's why we'll do a thorough investigation, we'll look at the processes we have in place and we'll make any changes if appropriate."
Seetal said the company did everything required of it after the spill, including reporting to the federal and provincial governments.
"We're absolutely taking this situation seriously," she said.
The company is working with the Western Canada Marine Response Corporation to complete the clean-up, Seetal said.
Seetal said the company is also conducting its own internal investigation to make sure such a spill doesn't happen again.
Inlet users concerned about process
News of the spill concerned the Burrard Inlet's Tsleil-Waututh First Nation, which used the accident to call for a moratorium on new pipelines.
"This incident reveals that the government's response plans are inadequate if they cannot, or will not, communicate with First Nations or local government's after the spill," said Carleen Thomas, the ambassador of the Tsleil-Waututh Nation Sacred Trust Initiative.
The spill happened Saturday night, but the First Nation wasn't told of the spill until Tuesday, and the media wasn't alerted until Thursday.
"The provincial and federal governments talk about world-class oil-spill response, but this shows that they are totally unprepared to deal with the oil products that are currently moving through the province, never mind the qualities of oil that new pipelines would bring," Thomas said.