Vale has reached out to Petrobras for help in dealing with a possible oil leak from Polaris Shipping's Stellar Banner as it lays partially submerged in waters off the coast of Brazil.

The severely listed 300,630-dwt iron-ore carrier (built 2016) has been stranded 100 km off the city of Maranhao, outside Ponta da Madeira Maritime Terminal's access channel, since Wednesday morning.

Vale said it has asked oil giant Petrobras to send an oil spill recovery vessel to the site to contain potential spills from the Polaris-owned ship.

The Brazilian Institute of Environment and Natural Renewable Resources has authorised movement of vessels to the city's coast, Vale said.

Vale said it is also hiring salvage specialists, in addition to one hired by Polaris, to expedite the oil removal plan, and has requested offshore ocean booms to help contain any spillage.

The company is also checking on availability of helicopters to move personnel to the location after 20 crew members were safely removed from the ship on Wednesday.

Reports suggested the vessel had a possible crack in its hull after suffering bow damage upon leaving the terminal.

Polaris, which is listed in Equasis as both owner and manager of the Marshall Islands-flag Stellar Banner, said Friday a slight oil sheen observed at the site is residue of dead oil that was on deck, not the leakage from a fuel tank.

"Therefore, as per harbour master’s decision, the oil fence has not been installed. The anti-pollution team are on site as a precaution to closely monitor the situation," the company said.

It added that a salvage team has a arrived to carry out an assessment to safely remove the ship.

"The utmost priority is to minimise any impact to environment, for which Polaris has committed all efforts and resources to ensure that the Stellar Banner does not pose a risk to the environment," the company said.

The shipowner had said on Thursday that the VLOC made contact with an unidentified shallow seabed after leaving the terminal in the northern Brazil city Maranhao on Monday night, at around 9:30pm local time (0030 GMT Tuesday).

“As a result of the incident, some ballast water tanks and void space suffered damage although the extent of damage to be further established,” said Polaris. “All cargo holds are believed to be intact and the situation is under control.”

Polaris claimed Thursday that reports of a leak from the ship are speculative.