The United States on Friday dispatched an envoy to Ethiopia to seek an end to renewed fighting and condemned neighboring Eritrea for re-entering the conflict in the northern region of Tigray.

Mike Hammer, the US special envoy for the Horn of Africa, will head this weekend to Ethiopia and "convey that all parties should halt military operations and engage in peace talks," White House Press Secretary Karine Jean-Pierre said.

"We condemn Eritrea's re-entry into the conflict, the continuing TPLF offensive outside of Tigray and the Ethiopian government's air strikes," she told reporters, referring to the rebel Tigray People's Liberation Front.

Fighting resumed last week in the northern region after a five-month lull, dashing hopes of peacefully resolving the nearly two-year war and of ending a humanitarian crisis in which Tigray has suffered widespread hunger.

"There is no military solution to the conflict," Jean-Pierre said.

"All parties should exercise restraint and we urge de-escalation by all actors, particularly so that there can be a resumption of humanitarian relief and basic services to all parties in need."

Hammer, a veteran US diplomat, took on the role in June and the following month visited Ethiopia in a bid to help launch peace talks, which never began due to disputes between the government and TPLF even while the ceasefire was holding.

The two sides have traded blame for starting the latest round of hostilities.

The TPLF, once Ethiopia's dominant force, has said that historic rival Eritrea again sent in forces as part of a major offensive with Ethiopian troops.

Eritrea, one of the world's most closed nations with one of its most authoritarian governments, has been accused of heinous violence in the conflict.

Amnesty International said that Eritrean forces at the start of the conflict in November 2020 massacred hundreds of civilians in the ancient city of Axum.

After months of denial that Eritrean troops had crossed the border, Ethiopian Prime Minister Abiy Ahmed in March 2021 admitted to their presence and promptly announced their departure.

Abiy won the Nobel Peace Prize for his reconciliation with Eritrea but has fallen out of favor with the United States, a longtime Ethiopian ally which voiced revulsion over the violence in Tigray, where US Secretary of State Antony Blinken has spoken of "ethnic cleansing."

President Joe Biden's administration as of January 1 booted Ethiopia out of a key trade agreement that allowed duty-free access, outraging segments of the growing Ethiopian-American community which said the United States was ceding influence to rival powers such as China.

Ethiopia's ambassador in Washington, Seleshi Bekele, met Thursday with senior officials including Deputy Secretary of State Wendy Sherman and called on the United States to condemn the TPLF which he said was to blame for breaking the ceasefire.

Access to northern Ethiopia is severely restricted and Tigray has been under a communications blackout for over a year.

TPLF spokesman Kindeya Gebrehiwot earlier told AFP that a major offensive was coming from Eritrea.

Combat had been concentrated around the southeastern border of Tigray, with the rebels pushing into the neighboring Amhara and Afar regions, sending residents fleeing.

The fighting so far has not terminated relief efforts, with UN spokesman Stephane Dujarric saying that 17 trucks distributed fertilizer in Tigray this week for farmers in their planting season.

Abiy sent troops into Tigray to topple the TPLF in November 2020 in response to what he said were rebel attacks on federal army camps.