An environmental “looting” spree is threatening biodiversity and pristine forests across 15 countries in central and eastern Europe, the UN has warned.

Environmental crimes such as illegal logging, fishing, poaching and the caviar black market are putting “high pressure” on ecosystems in the Danube-Carpathian region, according to a report by the UN Environmental Programme (Unep) and WWF.

At least one species of Danube sturgeon has become extinct due to the €22m-a-year black market caviar trade, with three other species now critically endangered, and one so rare that it can no longer be monitored.

Up to 36 million birds are being stolen or killed in the Mediterranean annually, the report says, with many ending up on plates in Italian and Maltese restaurants.

“The looting of these natural resources undermines development and deprives governments of the money they need to promote jobs, education and health services”, said Erik Solheim, Unep’s director. “These resources should rather be a solid foundation for future generations”.

Speaking after a meeting with Michael Gove in London this morning, Solheim added that the UK environment minister had give him “a very strong commitment to enforce the [conservation] laws and ensure that these crimes are brought to court and stopped.”

Environmental crime is now the world’s fourth largest type of criminal activity, valued at between $91bn and $258bn per year. The cost of illegal logging to Romania alone has been estimated at €5bn over the last two decades.

Climate change is increasingly adding to problems of environmental mismanagement, with forest fires in countries such as Bulgaria all but wiping out many monocultural plantations of non-native tree species.

Irene Lucius, one of the report’s authors, said this also provided an opportunity, however, as “it becomes increasingly evident that natural forests are more resilient to climate change and that these areas that have been devastated by forest fires should be replanted by native trees.”

Some populations of large carnivores such as bears, wolves and lynx are now recovering as a result of better enforcement of EU nature directives, and are being sighted in countries where they had been extinct, such as Denmark and Austria.

Logged areas in the Apuseni mountains, Romania. Photograph: Kathrin Lauer/Alamy Stock Photo

Most data on large mammals comes from hunters who have an interest in overstating population numbers, but only between 350 and 450 bears are thought to be left in Ukraine – compared to an estimated 6,000 in Romania, although this has created its own problems.

Solheim said that airlines and the tourist industry may be engaged in fundraising for projects that give local people a stake in nature conservation, ahead of a conference on wildlife crime in London next year.

Ukraine emerged from the UN report as the Carpathian region’s worst performer for forest conservation.

“Much more wood is being exported than is being cut each year in Ukraine, which indicates that there is a lot of illegality going on,” Lucius said.

“In Slovakia and Bulgaria, there is also a high level of certainty of illegal wood felling and in Moldova the tragedy is that the Romanian forest is being cut down because of poverty, by poor people who need firewood in winter.”

“Europe’s last remaining old-growth forests and their biodiversity are disappearing at alarming rates,” added Marco Lambertini, WWF’s international director.