Wolves were reintroduced at the Yellowstone National Park in 1995, in part to manage the rising elk park population

A conservation group on Monday more than doubled a reward for information on who was behind last month's shooting of a rare white wolf at Yellowstone National Park.

The severely injured female dubbed "White Lady" was found by hikers on April 11 near Gardiner, Montana, and had to be euthanized.

Park officials last week offered a reward of up to $5,000 for information on who shot the animal described as "one of the most recognizable and sought after by visitors to view and photograph."

An advocacy group in Montana said on Monday it would more than match the award offered by Yellowstone officials.

"We are receiving more money and I suspect the award we are offering is getting up to $5,500," Marc Cooke, president of the Montana-based Wolves of the Rockies, told AFP.

"There is an outcry on the part of wildlife enthusiasts to get the individual that is responsible for this."

Cooke said he suspects hunters angered by the presence of wolves in Yellowstone were behind the shooting.

"What's going on is because of the individuals that make a living in that area off of hunting, the wolves have disrupted their ability to acquire or to hunt trophy elk," he said.

"Somebody is taking matters into their own hands and doing their own form of private wildlife management—in other words poaching wolves."

The wolf that was shot was 12 years old—twice the age of an average wolf in the —and had 14 living pups, park officials said.

It was one of only three white wolves in Yellowstone.

Wolves were reintroduced in Yellowstone in 1995, in part to manage the rising elk park population.

Officials say the number of wolves in the park has fluctuated between 83 and 104 since 2009.