Greenpeace activists today blocked operations of Malaysian palm oil trader IOI at Rotterdam Port in the Netherlands, accusing it of forest destruction and child labour, but other traffic at Europe's busiest port was unaffected, a port spokesperson said.

Ten activists are blocking IOI, one of the world's biggest producers and traders of palm oil, from accessing its refinery, and the Greenpeace ship Esperanza is preventing oil from being unloaded from incoming tankers, Greenpeace said.

The action, which began mid-morning, was focused only on one mooring place used for palm oil coming from Indonesia, and was therefore not disrupting other traffic, port spokesperson Tie Schellekens said.

Rotterdam mayor Ahmed Aboutaleb had travelled to the spot in order to seek a compromise.

"There is no resolution yet," Schellekens said.

IOI could not immediately be reached for comment.

In April, the Roundtable for Sustainable Palm Oil (RSPO) withdrew IOI's 'sustainability certification' after allegations the company had illegally chopped down rainforests in Indonesia and planted palm crops on peatland.

But the body announced in August that IOI had satisfied conditions for the suspension to be lifted, a move that has sparked sharp criticism from environmental groups.

- Reuters