Ethiopia's army chief has accused the head of the World Health Organization of procuring weapons for the Tigray People's Liberation Front (TPLF), which is fighting federal troops.
Hundreds have died in the conflict in Tigray since the beginning of November.
Dr Tedros Adhanom Ghebreyesus is Tigrayan and was health minister in a previous Ethiopian government, which was led by the TPLF.
He has not yet responded to the BBC's request for comment.
Gen Berhanu Jula said in a press conference that Dr Tedros had "left no stone unturned" to support the TPLF and help get them weapons but did not provide any evidence to support his allegations.
"We don't expect him to stand on the side of Ethiopians and condemn these people.
He has been doing everything to support them, he has campaigned for neighbouring countries to condemn the war," said Gen Berhanu.
"He has worked for them to get weapons."
After being voted in as the head of the WHO in 2017, Dr Tedros became well known at the beginning of the coronavirus pandemic and is now arguably the highest-profile Tigrayan abroad.
Meanwhile, US President-elect Joe Biden's foreign policy aide has appealed for both sides to end the fighting.
"Deeply concerned about the humanitarian crisis in Ethiopia, reports of targeted ethnic violence, and the risk to regional peace and security," Antony Blinken tweeted.
The UN's refugee agency warns that a full-scale humanitarian crisis is unfolding.
More than 30,000 people have crossed the border from Ethiopia into Sudan.
Thousands of civilians are continuing to flee across the border, the UN Refugee Agency's representative for Sudan, Axel Bisschop told the BBC's Newsday programme.
"I spoke to a banker, some teachers, health workers, and they all say that it was too dangerous to be there... and they left by foot," he said.
What's the conflict about?
The TPLF dominated Ethiopia's military and politics for decades before Abiy Ahmed became prime minister in 2018.
He pushed through major reforms which some say sidelined the TPLF.
The feud escalated in September when Tigray held a regional election, defying a nationwide ban on all polls imposed because of the coronavirus pandemic.
Mr Abiy called the vote illegal.
Then fighting broke out on 4 November after Ethiopia's central government accused the TPLF of attacking a military base to steal weapons.
The TPLF has denied the attack.