Iconic Greenpeace ship the Rainbow Warrior on Monday prevented a cargo of coal from being unloaded at Poland's port of Gdansk as activists demanded authorities end coal use within a decade, the environmental group said.

"Poland must abandon burning coal by 2030," Pawel Szypulski, programme director of Greenpeace Polska, said in a statement referring to the target date for the phasing out of coal use in the European Union.

Under the 2015 Paris climate treaty, the EU pledged to reduce its carbon emissions by 40 percent below 1990 levels by 2030.

Greenpeace activists also painted "stop coal" in large white letters on the side of the cargo vessel carrying the shipment of coal from Mozambique.

"Instead of caring for the safety of Poles and the Polish national interest, our government is defending the interests of the coal lobby and importers of foreign fuels," Szypulski added.

The Greenpeace ship the Rainbow Warrior. Image credit: Twitter

"The climate crisis is happening here and now," he said, pointing to a summer drought which has cost the Polish agricultural sector over one billion zloty (231 million euros, $255 million) in losses.

Poland's right-wing Law and Justice (PiS) government plans only a gradual reduction in dependence on coal for electricity production, from around 80 percent today to 60 percent in 2030.

Poland along with Hungary have rejected an EU bid for zero net greenhouse gas emissions by 2050, insisting this would hamper their economies.

European Commission president Ursula von der Leyen has pledged to propose a "green deal" for Europe in her first 100 days in office, which would see a carbon-neutral continent by 2050.