M23 rebels have seized Kavumu airport and are advancing toward Bukavu, South Kivu’s capital, as fighting intensifies in eastern DRC.

Rwandan-backed M23 rebels in eastern Democratic Republic of Congo have taken control of the strategic Kavumu airport, which serves Bukavu, the region's second-largest city, the rebel alliance and a civil security source said on Friday.

The rebels have been advancing south toward Bukavu, the provincial capital of South Kivu, since they seized Goma, the largest city in eastern Congo, at the end of last month.

The capture of Bukavu would mark an unprecedented expansion of M23's territorial control and deal a further blow to Kinshasa's authority in the east.

"The city of Bukavu can no longer hold," a civil society source in Bukavu said.

Two people who work at the airport, which is primarily used for NGO and military flights, told Reuters earlier on Friday that it had been effectively closed. Congolese forces had already removed equipment, including drones and military aircraft.

A spokesperson for the rebel alliance, which includes M23, stated in a post on X that the rebels were in control of the airport and surrounding areas.

A member of the civil security service confirmed this to Reuters, while a UN source, a diplomatic source, and an M23 source had earlier said the rebels had reached the airport.

Meanwhile, Congolese President Felix Tshisekedi was seeking international support to address the crisis.

He traveled to Germany to attend the Munich Security Conference, the presidency said in a statement on social media on Friday. A source at the presidency added that he would head to Addis Ababa on Friday evening to attend the African Union summit on Saturday.

The conflict is expected to be a key topic at the annual two-day meeting in the Ethiopian capital.

The UN refugee agency expressed concern on Friday over the "rapidly deteriorating" situation, stating that the war had left around 350,000 displaced people without shelter.

In a video filmed in Kavumu by a local resident and seen by Reuters, men in military fatigues were seen walking through the town while gunfire could be heard.

Earlier on Friday, rebels seized the town of Katana, located 11 km (7 miles) from Kavumu, where the airport is situated, according to three sources.

A video taken by a Katana resident also showed armed men walking through the town.

"M23 soldiers are blocking the road and are heading towards Kavumu—they already have control of Katana," the resident said.

The town of Kabamba, north of Katana, was taken on Thursday, according to three sources.

As the fighting continues in the east, a heavier military presence has been observed throughout the capital, Kinshasa, some 1,600 km (1,000 miles) west of Goma, over the past week, according to a Reuters reporter.

Following the fall of Goma, protesters in Kinshasa attacked a UN compound and embassies, including those of Rwanda, France, and the United States, expressing anger over what they perceived as foreign interference. Looters also ransacked the Kenyan embassy.