Thousands of Romanians marched in the capital Bucharest and other cities on Sunday in protest against widespread illegal logging, which is believed to be behind the deaths of two forest workers in the past two months.

It's estimated that 4,000 people marched toward the water and forest ministry in downtown Bucharest, banging drums and chanting "Our forest is not your commodity," and "Thieves", according to local TV stations.

The protests, organized by Greenpeace Romania and other environmental groups, demanded thorough criminal investigations into the deaths and attacks against forest workers, as well as immediate upgrades to the country's automated logging tracking system and tighter legislation.

The Silva trade union federation says six foresters have been killed in recent years while another 650 forest workers were beaten, attacked with axes or knives or even shot at after catching illegal loggers in the act.

They include Raducu Gorcioaia, who was found dead in his car with head wounds on September 12 near a forest in Iasi county in eastern Romania, and Liviu Pavel Pop, who was shot dead on October 16 in the northwestern Maramures county. Police are still investigating both deaths.

Romania, which is home to some of Europe's last remaining virgin forests and diverse wildlife, is losing an estimated three to nine hectares of forest per hour due to illegal logging, Greenpeace studies have shown.

Smaller marches took place in other Romanian cities on Sunday, with protesters carrying signs which said "Climate emergency" and "Save the forest."