Uncertainty surrounded the fate of another lion from Zimbabwe's Hwange National Park Saturday after a conservation group reported that Jericho, brother of the lion slain by American dentist Walter Palmer, had also been killed.

"It is with huge disgust and sadness that we have just been informed that Jericho, Cecil's brother has been killed at 4pm today," the Zimbabwe Conservation Task Force, which broke the news of Cecil's killing, said in a statement on its Facebook page.

"We are absolutely heart broken. We will update you all as soon as we have more details," the statement added.

The announcement was swiftly picked up by global media, causing consternation among animal lovers who were outraged by Palmer's killing of Zimbabwe's best-known lion, renowned for his black mane.

But the Friends of Hwange Trust urged the public to treat the ZCTF's announcement with caution.

"Please know that reports stating that Jericho - the other half of Cecil the lion's coalition - was shot today appear to be UNTRUE."

The charity admitted however it did not yet have "definite proof" of its counter claim.

Hwange park authorities were unavailable for confirmation Saturday evening.

Earlier Saturday, Zimbabwe's parks authority announced restrictions on hunting around Hwange park, including an immediate suspension of the hunting of lions, leopards and elephants.

Palmer paid $55,000 to shoot Cecil outside Hwange park earlier this month with a bow and arrow. He and a guide then spent 40 hours tracking the wounded animal before finishing him off with a gun.

Palmer, who is being investigated by the US government over Cecil's death, has apologised and said he was misled by his guide.