Minister for Foreign Affairs Simon Coveney has described as "very worrying" reports emerging of "significant civilian fatalities and injuries" in Ethiopia's Tigray region after an airstrike at a market, which is said to have killed at least 43 people.

Residents have said that new fighting has flared in recent days north of the regional capital Mekelle.

Ethiopian military spokesman Colonel Getnet Adane did not confirm or deny the incident. He said air strikes were a common military tactic and that government forces do not target civilians.

The bomb hit a market at around 1pm today, according to a woman who said her husband and 2-year-old daughter had been injured.

"We didn't see the plane, but we heard it," she told Reuters today. "When the explosion happened, everyone ran out. After a time we came back and were trying to pick up the injured."

Mr Coveney said this evening that "if civilians have been deliberately targeted, that's a war crime".

"Int[ernational] community needs to ask hard questions and speak up," he said. "Certainly Ireland will."

The EU's chief diplomat, meanwhile, has decried the situation as "appalling" and pleaded with the world to "wake up and take action".

Josep Borrell called the strike "yet another attack adding up to the horrific series" of humanitarian law and human rights violations, atrocities and ethnic violence in Tigray.

'Volatile' situation

The woman said the market had been full of families, and she did not see any armed forces in the area. "Many, many" people had been killed, she said.

Reuters could not independently verify her account. She and other sources asked not to be identified for fear of reprisals.

The medical official confirmed at least 43 fatalities, citing witnesses and first responders.

A spokesperson for Prime Minister Abiy Ahmed and the head of a government task force on Tigray did not respond to requests for comment on the incident.

UN Secretary-General Antonio Guterres is deeply alarmed by the reports of civilian casualties from an airstrike, UN spokesman Stephane Dujarric told reporters in New York, calling on the parties to the conflict to obey international law.

"We have requested access to the area to assess the situation and see how we can provide assistance, but so far we have not been able to. The situation in the area remains very, very volatile," Dujarric said.

Senior U.N. aid official Ramesh Rajasingham called on the Ethiopian authorities to carry out "a prompt and effective investigation into this attack."

News of the airstrike came as Ethiopian officials counted ballots from national and regional parliamentary elections held this week in seven of the nation's 10 regions.

No voting was held in Tigray, where the military has been battling forces loyal to the Tigray People's Liberation Front (TPLF), the region's former ruling party, since November. Security concerns and problems with ballot papers also delayed voting in two other regions.

Residents reported that TPLF forces had entered several towns north of Mekelle in the past three days, withdrawing from one of them within hours.