(AFP) - Ethiopia's military launched air strikes on the capital of the war-battered Tigray region on Monday, a dramatic escalation in the year-long conflict.

The government initially dismissed reports about the bombardments on Mekele as an "absolute lie" but state media later confirmed the air force had struck Tigray People's Liberation Front (TPLF) targets.

A senior official at Tigray's largest hospital said three people had been killed, including two children.

They were the first air raids on Mekele since the early stages of the war in northern Ethiopia that has killed untold numbers of people and triggered a deep humanitarian crisis.

The bombardments -- reported by residents, humanitarian officials and diplomats -- came as Prime Minister Abiy Ahmed's government appeared to be pressing a new offensive against the TPLF, which dominated national politics for almost three decades before he took power in 2018.

The Ethiopian Press Agency said the raids hit media and communications equipment used by the TPLF, adding that "measures to prevent civilian casualties during the air strikes were done successfully".

Both the United Nations and the United States voiced alarm about the escalating violence.

One strike, the sources said, occurred near a cement factory on the outskirts of Mekele, the city held by the TPLF since it was recaptured from government forces in June.

The second hit the city centre near the Planet Hotel, often used by top officials from the TPLF, the region's former ruling party.

- 'Crying wolf' -

A government spokesman initially branded the reports as lies concocted by the TPLF "to misguide the international community" and apply pressure on Ethiopia, the second most populous country in Africa.

"There is no reason, or no plan, to strike civilians in Mekele, which is a part of Ethiopia, and home to our own citizens. This is absolute lie," Legesse Tulu, head of the Government Communication Service, told AFP.

Ethiopia's foreign ministry accused the TPLF of "crying wolf" and trying to cover up alleged attacks on civilians in Amhara and Afar, the regions neighbouring Tigray where the fighting has spread.

Dr Hayelom Kebede, research director at Mekele's Ayder Referral Hospital, told AFP that "many casualties" were coming to the facility and that three people -- including two children -- had been killed.

TPLF spokesman Getachew Reda said on Twitter that government forces were "losing big" and the aerial assaults were designed to inflict civilian casualties as revenge, noting that Monday was market day in Mekele.

UN chief Antonio Guterres was "deeply concerned" about the escalation of the conflict and called for all sides to avoid targeting civilians and to stop fighting, his spokesman Stephane Dujarric told reporters.

US State Department spokesman Ned Price issued a similar entreaty.

"We urge all parties to end hostilities immediately and for the Ethiopian government and the TPLF... to enter into negotiations without preconditions toward a sustainable ceasefire.”

Since the fighting first erupted in November, nearly two million people have been displaced, and there have been many reports of atrocities including massacres and mass rape.

The war has also soured relations between Ethiopia and Western powers, including the United States, long a crucial ally but which has now threatened sanctions.

- 'Break the siege' -

The air strikes came as the TPLF appeared to move south of Tigray towards Dessie, a city in Amhara where tens of thousands have sought refuge from the rebel advance since July.

One resident told AFP that Dessie was "flooded" with displaced civilians arriving from Wuchale, which lies to the north.

Legesse said the TPLF had in recent days used heavy weaponry on Wuchale, and accused the rebels of killing more than 30 civilians there.

At the weekend, Getachew said rebels had taken Wuchale -- a claim denied by a military official in Amhara.

Getachew said the rebels would march all the way to Addis Ababa if necessary.

"If that's what it takes to break the siege on Tigray, why not?" he told AFP by text message.

The rebels have justified their push into Afar and Amhara as necessary to prevent government forces from regrouping and to break what it describes as a humanitarian siege of Tigray.

The conflict erupted in November after Abiy sent troops to Tigray to topple the TPLF.

The 2019 Nobel Peace laureate -- who was sworn into a new term in office just two weeks ago -- said the deployment came in response to TPLF attacks on army camps.

© Agence France-Presse