Ethiopian soldiers arrested nine members of Tigray People’s Liberation Front, which led the region until being overthrown last year. The ongoing military campaign has left nearly 2.3 million people, or half of the population, in need of aid.
The Ethiopian army has said it killed four senior members of the Tigray region's ruling party targeted in a military offensive.
Ethiopian soldiers also arrested nine members of the Tigray People's Liberation Front (TPLF), who led the region until being overthrown last year in the military campaign.
Those killed included a TPLF spokesperson, Sekoture Getachew, and the former head of the Tigray finance bureau, Daniel Assefa, according to Brigadier General Tesfaye Aylew, cited by Fana Broadcasting Corporate.
The former director of the Ethiopian Broadcasting Authority and a journalist close to the party, Abebe Asgedom, were also killed.
A senior Ethiopian general said in a video clip posted on social media this week that Eritrean troops had entered the country uninvited while his soldiers were battling a rebellious force in the northern region of Tigray.
The video, whose authenticity Reuters could not independently verify, shows Major General Belay Seyoum addressing a meeting in the Tigrayan capital Mekelle in late December.
"An army that we don't want has entered. Are we the one that invited them? No," he said. "They just entered by themselves, and this has to be made clear."
Ethiopian Prime Minister Abiy Ahmed's spokesperson, the head of Ethiopia's emergency task force on Tigray and a military spokesperson did not respond to questions about the footage.
Neither did Eritrea's information minister, Yemane Meskel.
Belay's comments could alarm Western allies concerned that such an incursion might aggravate the conflict in Tigray, which has already killed thousands.
UN reports ongoing fighting
A UN report posted online late on Thursday said fighting is still going on in several parts of Ethiopia's northern Tigray region and almost 2.3 million people, or nearly half of the population, need aid.
It said food supplies were very limited, looting was widespread and insecurity remained high.
Federal government troops are fighting the TPLF and the whereabouts of TPFL leader Debretsion Gebremichael, other members of the party's central committee and many high-ranking former military officers remains unknown.
The findings in the humanitarian report stem from two missions conducted at the end of December by UN and government agencies.
They said the humanitarian situation was dire and two out of four refugee camps in Tigray remained inaccessible.