UNITED NATIONS, March 19 (Xinhua) -- Deadly drone strikes by Sudan on the Chadian side of the town of Tine, which is on the Sudan-Chad border, emphasize the risk of broader regional destabilization, a UN spokesman said Thursday.

"We are alarmed by reports that a drone strike yesterday (Wednesday) killed at least 17 civilians and injured many more," said Farhan Haq, deputy spokesperson for the UN secretary-general. "This attack highlights the devastating human cost of the Sudanese conflict and how rapidly the frontlines are shifting, with border communities increasingly exposed to violence."

During a regular briefing, the spokesperson told reporters that the intensifying use of increasingly powerful drones by both warring parties is expanding the battlefield and accelerating civilian harm across the country.

Attacks of this nature also emphasize the risk of broader regional destabilization, with neighboring countries at growing risk of being drawn into the fighting, Haq said.

On Wednesday, Chadian President Mahamat Idriss Deby Itno ordered the "complete closure" of the border, according to a statement issued by the Chadian presidency. The president instructed Prime Minister Allamaye Halina to dispatch a government delegation to the site to assess both human and material damage, and ordered the National Army to retaliate against any attack originating from Sudan.

"We call on the warring parties to immediately de-escalate the fighting, comply with international humanitarian law and return to the negotiating table to pursue a sustainable resolution to this conflict," Haq said.

Tine is a key border crossing, though seasonal rains frequently disrupt traffic into the Darfur and Kordofan regions of western Sudan from Chad.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said that despite many challenges, the United Nations and its partners continue to respond to needs across Sudan.

OCHA said Save the Children delivered 30 metric tonnes of medical and nutritional supplies to Tawila in North Darfur last week. The supplies were expected to support more than 80,000 children and 57,000 adults and will enable 20 health facilities and mobile clinics to continue serving displaced communities for six months.

The International Organization for Migration also reported that the overall number of displaced people in Sudan this week has fallen, with close to 9 million people now estimated to remain displaced within Sudan's borders. Returns to Khartoum and the eastern states continue.

In January, the United Nations said that Sudan, the world's largest displacement crisis, had an estimated 13.6 million people uprooted by the fighting, around 9.3 million internally displaced and 4.3 million seeking refuge in neighboring countries.

Overcrowded living conditions, poor sanitation and disrupted services have fueled outbreaks of cholera, malaria, dengue and measles across much of the country, the world body has said.

The World Food Programme (WFP) has said that famine conditions have been confirmed in El Fasher and Kadugli, with risk of famine projected in 20 additional areas across Greater Darfur and Greater Kordofan.

WFP said that an estimated 21.2 million people, 45 percent of the population, face high levels of acute food insecurity, according to the latest Integrated Food Security Phase Classification report.

OCHA said its partners are calling for more funding, as well as rapid, safe, unhindered and sustained access to scale-up assistance. The 2026 Humanitarian Response Plan requires 2.9 billion U.S. dollars to reach more than 20 million people across Sudan. It is only about 16 percent funded, with 454 million dollars received so far.

The UN Refugee Agency and its partners also require an additional 1.6 billion dollars this year to support refugees and host communities in neighboring countries. ■