Tigrayan authorities on Friday accused Ethiopia's government of carrying out a drone strike on civilians, less than 48 hours after the warring parties signed a deal to end their bloody conflict.
The breakthrough agreement sealed in South Africa has been hailed internationally as a key step towards stopping a war that began exactly two years ago on Friday.
A spokesman for the rebel Tigray People's Liberation Front (TPLF) alleged that Prime Minister Abiy Ahmed's government had carried out attacks against civilians in the Tigrayan city of Maychew on Thursday.
"According to sources at Lemlem-Karl Hospital, drone of #Ethiopia has attacked civilians," Kindeya Gebrehiwot said on Twitter.
"There was also shelling of artillaries in the same city that killed & wounded civilians. This happens after signing the peace agreement at #Pretoria," he said.
AFP was not able to independently verify the claims.
Access to northern Ethiopia is severely restricted and Tigray has been under a communications blackout for more than a year.
There was no immediate response from Ethiopian government officials or the African Union (AU) to requests from AFP.
The agreement signed on Wednesday says both sides agreed "to permanently silence the guns" and to a "programme of disarmament, demobilisation, and reintegration for the TPLF combatants."
But observers say that key details and a clear roadmap that would help sustain momentum are absent, and distrust runs deep.
Even as the AU-led negotiations began in Pretoria last week, fierce fighting was under way in Tigray between TPLF fighters and federal forces backed by soldiers from neighbouring Eritrea.
Ethiopia's northernmost region has been in the throes of a severe humanitarian crisis due to lack of food and medicine, as well as limited access to basic services.
Observers and diplomats have warned of the difficult road ahead, with the EU's foreign policy chief Josep Borrell on Friday saying that arriving at a permanent ceasefire was "going to be very difficult."
Speaking to reporters on the sidelines of the G7 foreign ministers' meeting in the German city of Muenster, Borrell acknowledged that the agreement was "good news," but cautioned: "Making peace is much more difficult than making war."
"The world is looking at Ukraine and blaming Russia. But Ethiopia is for sure the worst humanitarian crisis... and war in the last two years," Borrell said.
Abiy, a Nobel Peace Prize laureate, sent troops into Tigray on November 4, 2020 to topple the TPLF, the region's ruling party, in response to what he said were attacks on federal army camps.