The shipment, which was confiscated late Saturday, arrived on an Ethiopian Airlines passenger flight, prompting an immediate launch of investigations, the SUNA news agency reported.

Authorities were informed of "the arrival of a weapons shipment from Addis Ababa on an Ethiopian Airlines flight" into Sudan, SUNA said.

"It was immediately confiscated by customs authorities."

SUNA quoted officials as saying that the weapons had originally been sent from Russia to Ethiopia in May 2019 and were held by authorities there for two years.

"Without prior warning, authorities in Addis Ababa allowed for its shipping into Khartoum on a passenger flight," the report added.

The shipment of 72 boxes reportedly contained weapons and night-vision binoculars.

"There are suspicions that they were meant to be used in anti-state crime, to impede the democratic transition, and prevent transition to civilian rule," SUNA reported.

Sudan has been undergoing a rocky transition since the April 2019 ouster of Islamist president Omar al-Bashir following mass protests against his rule.

The country is currently led by a joint civilian-military ruling council.

The development comes at a time of souring relations between Khartoum and Addis Ababa over Ethiopian farmers' use of a fertile border region claimed by Sudan.

The two countries have also been at odds over the Grand Ethiopian Renaissance Dam (GERD), in a regional dispute that involves Egypt.

Addis Ababa broke ground on the project in 2011.

Late last month, Ethiopian officials said they had thwarted an attack on the GERD by armed groups "who have been trained and armed by Sudan."

Sudan flatly denied the allegations, saying they were "baseless".

Ethiopia has been grappling with a grinding conflict in its northern Tigray region since last November.

The fighting has sent tens of thousands of refugees into Sudan.