NAIROBI, Kenya (AP) — Tensions over the deadly conflict in Ethiopia are spreading well beyond its cut-off Tigray region, as the federal government on Thursday said some 150 suspected “operatives” accused of seeking to “strike fear and terror” throughout the country have been detained.

The statement said the suspects “happen to be ethnically diverse,” but concerns remain high among ethnic Tigrayans amid reports of being singled out by authorities.

The statement came as rallies are expected Thursday in support of the federal government’s military offensive in the northern Tigray region against a regional government that Nobel Peace Prize-winning Prime Minister Abiy Ahmed and his government regard as illegal.

Close to 10,000 Ethiopian refugees have already fled the weeklong conflict into neighboring Sudan, where local authorities are already warning they are overwhelmed. They are preparing for up to 200,000 arrivals.

Ethiopia’s prime minister has rejected international pleas for negotiation and de-escalation, saying that cannot come until the Tigray People’s Liberation Front ruling “clique” is removed and arrested and its heavily stocked arsenal is destroyed.

In a new statement Thursday, Abiy asserted that the western part of the Tigray region had been liberated, and accused the TPLF rulers of seeking to “destroy Ethiopia.”

What appeared to be a sudden slide toward civil war has been months in the making. Abiy after taking office in 2018 announced sweeping political reforms that won him the Nobel but marginalized the TPLF, which had dominated Ethiopia’s ruling coalition. The TPLF later left the coalition and in September held a local election in defiance of the federal government.

Each side now regards the other as illegal, and each blames the other for starting the fighting.

Communications and transport links remain severed in the Tigray region, making it difficult to verify claims, while the United Nations and others warn of a looming humanitarian disaster as food and fuel run short for millions of people.

There is no sign of a lull in the fighting that has included multiple airstrikes by federal forces and hundreds of people reported dead on each side. It is not clear how many of the dead are civilians.

The effects of the conflict risk drawing in Ethiopia’s neighbors, notably Sudan, whose leaders are under pressure from the international community, Ethiopia’s federal government and now the government of Eritrea, which the TPLF accuses of joining the fighting at Ethiopia’s request.

Experts fear that the Horn of Africa, one of the world’s most strategic regions, could be destabilized despite Abiy’s past peacemaking efforts.

The top U.S. diplomat to Africa, Tibor Nagy, spoke with Ethiopia's foreign minister on Wednesday “to urge again immediate action to restore peace and de-escalate tensions,” a State Department spokesperson said in an email. “The protection and safeguarding of American citizens and all civilians is our top priority.”

More than 1,000 citizens of various countries are stuck in the Tigray region, the U.N. humanitarian chief in Ethiopia, Sajjad Mohammad Sajid, has told the AP.

Inside the Tigray region, long lines have appeared outside bread shops, and supply-laden trucks are stranded at its borders. Fuel is already being rationed.

“Every global agency, the U.N., is asking for a cease-fire but we haven’t seen any agreement, any willingness to dialogue,” U.N. refugee agency spokesman Kisut Gebreegziabher told the AP late Wednesday.