US President Joe Biden is sending his special envoy for the Horn of Africa to Ethiopia to push for an end to increased fighting that has worsened fears of an unfolding humanitarian disaster.

White House national security adviser Jake Sullivan announced the trip by envoy Jeffrey Feltman on Thursday, while urging Ethiopia’s government and the Tigray People’s Liberation Front (TPLF) to come to the negotiating table after nine months of conflict.

“Months of war have brought immense suffering and division to a great nation that won’t be healed through more fighting,” Sullivan tweeted.

“We call on all parties to urgently come to the negotiating table,” he said.

Prime Minister Abiy Ahmed’s federal troops and forces from the TPLF, which controls Tigray, have been battling since November in a war that has killed thousands of people and sparked a major refugee crisis. The conflict has been marked by ethnic killings and rape as a weapon of war.

Alliance with OLA

Earlier this week, TPLF forces said they were in talks to forge a military alliance with fighters from Ethiopia’s most populous region, Oromiya, heaping pressure on the government in Addis Ababa.

The leader of the Oromo Liberation Army (OLA) told Reuters news agency by phone on Thursday the group opted to join forces with the TPLF, which it bitterly opposed during its three decades in power in Ethiopia, because they now have a common cause.

“I hope we are going to squeeze this government and if possible – and I know it’s possible – we are going to overthrow this regime and stop this crisis,” said OLA leader Kumsa Diriba, who goes by the nom de guerre Jaal Marroo.

The government has designated both the TPLF and the OLA as “terrorist” organisations.

Feltman’s mission follows a trip earlier this month to Addis Ababa by US aid chief Samantha Power, who pushed all sides to end hostilities and warned of an impending “humanitarian catastrophe” if more aid cannot enter.