An oil spill incident at the Port of Brisbane on Sunday night has leaked five to ten tonnes of oil, which has impacted water birds, such as pelicans and cormorants.

In its initial inspection, Maritime Safety Queensland found small globules of oil in the water concentrated near the outer Fisherman Island wharves area, with some coating of oil on wharf structures.

The incident, however, has not affected shipping through the port. The cause of the spill is as yet still unknown.

Maritime Safety Queensland and Port of Brisbane oil spill response crews are said to be on standby with containment and clean-up equipment.

Queensland Transport Minister, Scott Emerson, as quoted by the Guardian, said an estimated ten tonnes of oil has been leaked into the water and about 1,400m along the outer wharves area has been impacted.

"We’re using booms at the moment there to contain the spill and then we’ll get the skimmers in to try to lift it up to take the oil off the water," Emerson added.

"We have had sightings already of pelicans being affected by the oil, and other wildlife, other birdlife."

Officials at the port have found four pelicans and one cormorant covered with oil.

According to AAP, apart from clean up costs, the fines for the oil spill could be up to $550,000 for individuals, or $11m for a company.

Image: Port of Brisbane. Photo courtesy of J Brew.