(Bloomberg) -- U.S. Secretary of State Antony Blinken called for an end to fighting in the Tigray region of Ethiopia and an international investigation of reported atrocities there.

In a statement Saturday, Blinken appealed for a cessation of hostilities between Ethiopia and the Tigray People’s Liberation Front and the removal of forces from neighboring Eritrea and Ethiopia’s Amhara region. The African Union and regional partners should then address the situation, he said.

Almost four months of conflict in Tigray have left thousands dead and forced millions to flee. Amnesty International last week accused Eritrean troops of massacring civilians in the Ethiopian town of Axum, killings that the independent Ethiopian Human Rights Commission is also investigating.

“We strongly condemn the killings, forced removals and displacements, sexual assaults, and other extremely serious human rights violations and abuses by several parties that multiple organizations have reported in Tigray,” Blinken said. “We are also deeply concerned by the worsening humanitarian crisis.”

Unrest emerged after Prime Minister Abiy Ahmed took office in 2018 and began consolidating power under his new Prosperity Party, sidelining the TPLF, which had been the pre-eminent member of the ruling coalition for decades.

Tigray went ahead with regional elections despite federal government calls to postpone them due to the coronavirus pandemic. Its leaders were also angered by plans to reshuffle the military leadership stationed in their territory and designate the TPLF a terrorist organization.

Fighting began in November after TPLF forces attacked a military base, and while Abiy declared victory within weeks, clashes continued. Ethiopian officials have denied that Eritrean forces are involved, while Eritrea has been silent.

The Ethiopian government and TPLF have yet to respond to Blinken’s appeal.

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