A ship carrying Indonesian plywood needed a police escort into the Port of Tilbury this week after Greenpeace activists formed a boat blockade in a bid to stop it unloading.

Greenpeace has called on UK environment minister Elliot Morley to seize the timber, which it alleges was illegally felled in Indonesia’s rainforests.

Activists tried unsuccessfully to board the MV Greveno, carrying tens of thousands of cubic metres of plywood, before occupying the lock gates at Tilbury and forming a boat blockade. A police flotilla allowed the vessel to dock and unload, while several protestors were arrested.

Greenpeace has tracked the ship, chartered by Pan Ocean, since it was loaded in early February. It claims the cargo was supplied by Korindo’s Ariabima Sari mill, which was found to be using illegal logs by an Indonesian government investigation in 2003.

Plywood onboard the MV Greveno also comes from a second company, Tjipta, which Greenpeace says sources logs from Sumatra, where illegal logging is threatening the survival of the Sumatran tiger.

Tilbury-based Charles Gee & Co Ltd, the UK shipping agent acting for Pan Ocean, said about 2,000m3 of plywood was unloaded at Tilbury for several UK timber importers. The ship was then headed for mainland Europe for further deliveries.

The TTF said it did not know whether Greenpeace claims about the shipment were accurate but confirmed that the Ariabima Sari mill did not take part in its scoping study.

Mark O’Brien, the TTF’s head of public affairs, said: “We do not want to walk away from Indonesia and boycott it. That will not help the Indonesian forestry sector who will continue to trade with other countries. We will use whatever market influence we have to change it.”