Illegal logging, mining, poaching and other environmentally destructive trade earned criminal gangs up to $258 billion last year, the United Nations said in a report published on Saturday.

The scale of crimes ranging from illegal gold mining by drug cartels in Colombia to pillaging forests by rebels in Democratic Republic of Congo is expanding two to three times faster than the global economy, the study by the U.N. Environment Programme (UNEP) and Interpol found.

"Environmental crime is growing at an alarming pace," Interpol Secretary General Juergen Stock said in a statement.

The amount spent by international agencies on combating environmentally damaging crime — $20-30 million — is just a fraction of its estimated value of $91-258 billion, it said.

Trafficking products from endangered wildlife, including tusks harvested by the decimation of one quarter of the world's elephant population over the last decade, is worth between $7 to $23 billion a year, the report said.

Pointing to the mismatch between poachers' profits and government measures to fight them, ivory traffickers in Tanzania reap five times the size of the country's wildlife budget, or an estimated $10.5 million per year, it said.

An average 3,000 elephants were killed per year there over the last decade, the data showed.

"The vast sums of money generated from these crimes keep sophisticated international criminal gangs in business, and fuel insecurity around the world," UNEP Executive Director Achim Steiner said.

The report also highlighted complex carbon credit fraud cases that run into hundreds of millions of dollars.