A drone strike targeted Sudan's biggest naval base on Wednesday, an army source told AFP, marking the fourth straight day the seat of the army-backed government has come under attack.
It comes a day after the government severed ties with the United Arab Emirates, which it accuses of supplying rival paramilitaries with weapons used to attack the army.
Port Sudan on the Red Sea coast had been a safe haven, hosting hundreds of thousands of displaced people and United Nations offices, until Sunday when drone strikes blamed on the Rapid Support Forces (RSF) paramilitaries began.
Wednesday's drone strikes "were met with anti-aircraft missiles", the army source said on condition of anonymity because they were not authorized to speak to the media.
An AFP correspondent reported a series of explosions from the direction of the Flamingo Base, just north of the city.
Later Wednesday, residents reported air defenses in action against drones circling above the city.
War has raged since April 2023 between Sudan's regular armed forces and the RSF.
- 'Major escalation' -
Nearly 600 kilometers (375 miles) further south, "three drones attempted to strike airport facilities" in the army-held eastern city of Kassala on Wednesday, near the border with Eritrea, a security source said.
Witnesses told AFP they heard explosions from anti-aircraft missiles west of the city, which has also come under repeated attack this week.
In the city of Merowe in Northern state, around 420 kilometers from Khartoum, residents reported drones overhead being intercepted by anti-aircraft fire.
Nationwide, the war has killed tens of thousands of people and uprooted 13 million.
It has also effectively split Sudan in two, with the army controlling the center, north and east, while the RSF holds nearly all of Darfur in the west and parts of the south.
The RSF has not directly commented on this week's attacks on Port Sudan, about 650 kilometers from its nearest known positions on the outskirts of the capital.
A spokesman for UN chief Antonio Guterres on Wednesday called the drone strikes a "major escalation (that) could lead to large-scale civilian casualties and further destruction of critical infrastructure".
Port Sudan is the main entry point for humanitarian aid into Sudan, and Guterres spokesman Stephane Dujarric said the attacks "threaten to increase humanitarian needs and further complicate aid operations in the country".
Famine has been declared in some areas in Sudan and nearly 25 million people are suffering dire food insecurity.
The UN also has warned of more "human suffering in what is already the world's largest humanitarian crisis".
- 'Advanced weaponry' -
French medical charity Doctors Without Borders (MSF) said Wednesday its services in the northern River Nile state have been disrupted after drone attacks targeted a power plant in state capital Atbara.
The attacks caused a major power outage and affected the city's water treatment plant, disrupting access to clean water and risking a surge in waterborne diseases such as cholera, MSF said.
The attacks also scaled down production at the state's oxygen concentration factory, which provides health facilities with oxygen tanks.
MSF said such attacks on infrastructure "have a devastating impact on the health of the local communities" and harm "an already overburdened health system".
The drone campaign comes after the RSF in March lost control of nearly all of greater Khartoum.
The army-backed foreign ministry described the attack on Port Sudan as "a full-fledged crime of aggression", which it said was carried out with "strategic drones and advanced weaponry".
Sudan has accused the UAE of supplying the RSF with the weapons it has used to strike Port Sudan.
The UAE has repeatedly denied arming the RSF.
On Wednesday, it rejected the severing of ties, saying the decision was made by an administration that "does not represent the legitimate government of Sudan".
