A ship carrying hundreds of tonnes of possibly toxic industrial waste returned to Albania's largest seaport of Durres on Monday, months after setting sail to dispose of the material in Thailand.

The Turkish-flagged Moliva container ship, believed to be carrying around a hundred containers filled with suspicious waste, was expected to be tested by Albanian authorities.

"The ship is anchored in Durres about one kilometre from the port," Jim Puckett, director of the Basel Action Network (BAN) a non-governmental organisation that combats the export of toxic waste to developing countries, told AFP.

Puckett was at the Albanian port, awaiting the vessel’s expected docking in the afternoon.

“We would hope that the prosecutors team will be here when the ship arrives," Puckett said.

He urged them to "put the containers under high security watch and not allow them to be opened until it can be done in an organized way, in the public view, so that the contents can be sampled and later analysed,” he added.

The Moliva left Albania in early July and according to documents Albanian customs authorities at that time its cargo consists of industrial waste, specifically "iron oxide," whose export is authorised.

However, information passed on to BAN by a whistleblower suggests the cargo actually contains electric arc furnace dust (EAFD).

Classified as toxic waste, this dust must be stored and transported under very strict conditions.

Ultimately rejected by Thailand, the ship turned back and returned to Albania after several months at sea, with stopovers in Spain, Portugal, Italy, and Turkey.

The Durres prosecutor's office has launched an investigation into the smuggling of prohibited goods and has indicated it plans take samples of the samples for analysis upon the ship's arrival at Durres to determine whether the containers indeed contain toxic waste.

According to the paperwork on file the waste comes from the Elbasan steel plant in central Albania.

"If what we're saying is true and we're 95 percent sure that this is steel dust collected by filters at the steel plants in Elbasan, it is hazardous waste by international law," Puckett stated.

He called the export of the material "criminal".

The Durres prosecutor's office, which is working in cooperation with the European anti-fraud office (OLAF), ordered on Sunday the seizure of the containers upon their arrival to prepare for their opening under safe conditions.

The shipment of industrial waste from Western countries to be processed elsewhere in developing counties is a global business estimated to be worth between 44 billion and 70 billion euros annually according to environmental NGOs.