NAIROBI, Kenya (AP) — At least 30 armed Ethiopian troops and “large numbers” of refugees fleeing the fighting in Ethiopia’s northern Tigray region have crossed the border into Sudan, the state-run SUNA news agency reports, while one diplomat says hundreds of people have been reported killed on both sides of Ethiopia's conflict.

Ethiopia’s prime minister on Tuesday again vowed that his military will bring a speedy end to the week-long fighting in the heavily armed Tigray region and the removal of its leadership, which his government regards as illegal.

The troops from the Amhara region neighboring Tigray fled into Sudan’s Qadarif province Monday evening, the SUNA report said, citing witnesses. Local authorities have started to prepare a refugee camp for the fleeing Ethiopians, while aid groups warn of a brewing humanitarian crisis at the heart of the Horn of Africa region.

The Ethiopian troops turned themselves and their weapons in, and appealed for protection as fighting raged over the border, said a Sudanese military official on condition of anonymity because he was not authorized to brief reporters. Sudan has sent more than 6,000 troops to the border.

Ethiopia’s Nobel Peace Prize-winning prime minister, Abiy Ahmed, on Tuesday described his government's military campaign in the Tigray region as “law enforcement operations” that he said will end as soon “as the criminal junta is disarmed, legitimate administration in the region restored, and fugitives apprehended and brought to justice — all of them rapidly coming within reach."

Abiy has shown no sign of opening talks with the Tigray People's Liberation Front, which once dominated Ethiopia’s ruling coalition but is now regarded by the federal government as illegal. Feeling marginalized by Abiy’s political reforms, it broke away last year as the prime minister sought to transform the coalition into a single Prosperity Party. The TPLF defied the federal government by holding a local election in September.

Diplomats and others assert that the conflict in Tigray could destabilize the region and other parts of Ethiopia, Africa’s second-most populous country with 110 million people. Ethiopia has scores of ethnic groups and other regions that have sought more autonomy even as Abiy, who won the Nobel just last year, tries to hold the country together with exhortations of national unity.

Several hundred people reportedly have been killed on both the Ethiopian government side and the Tigray regional government side, a diplomat in the capital, Addis Ababa, told The Associated Press.

More than 150 citizens of European Union countries alone are thought to be in the Tigray region, which is increasingly cut off with airports and roads closed and communications largely severed, and governments are trying to ensure their consular protection, the diplomat added, speaking on condition of anonymity.

“There are so many uncertainties,” the diplomat said. “How far can Abiy go with this operation while keeping the possibility of, in the end, having a more or less peaceful solution? You need the support of the people.”

Experts worry that the longer the conflict lasts, the more difficult it will be for the federal government to bring the Tigray region back to Ethiopia's federation of regional states.

Magdy reported from Cairo.