A tanker carrying 750 tonnes of diesel sank Saturday off Tunisia's southeast coast.
The crew of the Xelo vessel had issued a distress call on Friday evening and sought shelter in Tunisian waters in the Gulf of Gabes in the morning.
Officials and the Environment Minister travelled to the port of Gabes to help oversee the response.
The Equatorial Guinea-flagged Xelo was headed from the Egyptian port of Damietta to Malta. Authorities believe a large spill would likely be avoided.
"**This is a cago of fuel oil or diesel, Environment Minister Leila Chikhaoui told the media. It is very different from oil in that fuel oil is much less dangerous and tends to evaporate fairly quickly. Regarding the waterproofness of the hull, we think the hull is still watertight and there is no leakage at the moment **[...] We are waiting for the weather to be better, especially in terms of wind and swell, to allow the divers to verify with more certainty the state of the hull and the state of the cargo and to proceed, of course, with the necessary measures such as pumping or bringing the ship closer to the coast in order to secure both the cargo, the engine oils and everything that follows."
If the seven-member crew has been rescued, the weather was still too poor to start maritime manoeuvres on Saturday.
The Tunisia branch of the World Wildlife Fund said it feared a "new environmental catastrophe in the region".
The district court in Gabes opened an investigation into the accident.