The brother of Cecil the lion, Jericho, has been shot dead by poachers, the Zimbabwe Conservation Task Force has said.
The organisation wrote on Facebook: “It is with huge disgust and sadness that we have just been informed that Jericho, Cecil’s brother, has been killed at 4pm today.
“We are absolutely heartbroken.”
However, a researcher monitoring the pride has disputed the claim.
“He looks alive and well to me as far as I can tell,” said Brent Stapelkamp, field researcher for the Hwange Lion Research Project which is monitoring the lion with a GPS tag.
It is thought Jericho had been protecting Cecil’s cubs.
The murder of 13-year-old Cecil by US dentist Walter Palmer on 1 July caused outrage when it was made public earlier this week.
Mr Palmer allegedly paid park guides $50,000 (£32,000) to kill the lion, who was a hugely popular attraction at the Hwange National Park.
More than 140,000 signatures have been gathered for a bid to send the Minnesota dentist to Zimbabwe to face justice.
The White House has said it will review the petition.
Zimbabwean authorities claim they are seeking extradition.
The county has now suspended the hunting of lions, leopards and elephants in the area while it investigates the killing of another lion in July.
A man from a private game park has been arrested over this case, officials said.