The Tigray People's Liberation Front, the party that controls most of the northern Ethiopia region of Tigray, accused Eritrea of attacking its troops.
In another development in the conflict, aid organizations suspended operations in an area northwest Tigray where 56 civilians were killed by an air strike over the weekend, the UN agency for humanitarian affairs UNOCHA said.
The TPLF spokesman Getachew Reda wrote on Twitter that the Eritrean military launched new attacks against our forces in Sigem Kofolo, located in Northwestern Tigray close to Sheraro town.
The communication network is down in the area and Reuters could not verify the attack.
Eritrean Information Minister Yemane Gebremeskel did not respond to requests for comment.
Ethiopia s military spokesman Colonel Getnet Adane and government spokesman Legesse Tulu did not respond immediately to requests for comment. Billene Seyoum, the spokeswoman for Prime Minister Abiy Ahmed, did not respond to a request for comment.
A lack of medicines, fuel, and other essential commodities was disrupting the response to the injured, the UNOCHA said in a statement announcing the suspension of operations after the air strike that hit a camp for internally displaced people late on Friday.
Humanitarian partners suspended activities in the area due to the ongoing threats of drone strikes, the agency told Reuters.
Death toll piled from air strikes and aid blockade in northern Ethiopia
The war broke out in the mountainous region of 5 million people 14 months ago, pitting Tigrayan forces against federal troops backed by their Eritrean counterparts.
The president of Eritrean Afwerki told the state-owned Eri-TV on Saturday that his troops would try to prevent Tigrayan forces from attacking his country or threatening the stability of Ethiopia.
Since the start of the war, Eritrean forces have fought against Tigrayan forces in support of Abiy's troops, but both nations spent the first five months of the conflict denying the Eritrean presence.
In June, the Eritrean troops withdrew from most of the region, the same month Ethiopian federal troops withdrew.
In July, Tigrayan forces withdrew from neighbouring regions they had invaded in July, in a move toward a potential ceasefire.
All sides, including Eritrea, have denied the parties to the fighting, according to a report by the parties to the fighting.
The conflict in northern Ethiopia has killed thousands of civilians and displaced millions.