Sudan's accusation that Israel bombed a Khartoum weapons plant last week has drawn attention to long-standing Israeli complaints of alleged Sudanese cooperation with Iran in smuggling weapons to Palestinian militants.
Sudan and Iran have been allies for decades and boosted military ties under a 2008 agreement. As part of that relationship, two Iranian warships docked at Port Sudan on Monday, in what both sides described as a "routine visit".
But, allegations that the two allies also cooperate in arms smuggling have grown since the October 24 explosions at Khartoum's Yarmouk weapons facility.
Khartoum complex raises suspicions
The Yarmouk military complex in Khartoum, Sudan following the alleged attack. A U.S. monitoring group says satellite images of the aftermath of an explosion at a Sudanese weapons factory suggest the site was hit by an airstrike, October 25 2012.
The Satellite Sentinel Project
, a U.S.-based monitoring group, says images of Yarmouk taken before and after the pre-dawn incident suggest the complex housed "highly volatile cargo" that exploded when struck by air-delivered munitions.
Sudanese authorities say four people were killed and blamed the destruction on Israeli warplanes.
Since the incident, Israeli defense commentators have claimed that the volatile cargo at Yarmouk included missiles made under Iranian supervision for smuggling through Sudanese and Egyptian territory to Palestinian militants in the Gaza Strip.
Israeli officials decline to comment on what happened at Yarmouk, but repeat their accusations of Sudanese-Iranian coordination in arms smuggling.
Sudan, Iran react to allegations
Speaking Tuesday, Sudanese and Iranian officials denied any Iranian involvement at the Yarmouk complex and accused Israel of looking for a false pretext to attack Sudan.
Sudanese Undersecretary for Foreign Affairs Mohamed Osman Rahamtalla says the Yarmouk incident is purely a Sudanese matter.
"We know the source of that attack and we have sent a very strong message against [the attackers]. Iran has nothing to do with this," he says.
Sudan says the apparent air strike was meant to damage its military capabilities.
Sunni-majority Sudan has been trying to improve those capabilities with the help of predominantly-Shi'ite Iran since the 1989 coup that brought President Omar al-Bashir to power.
Alliance rooted in Islam
Former U.S. special envoy to Sudan Andrew Natsios says a prominent Sudanese Islamist who supported the coup, Hasan al-Turabi, later approached Iran's Islamist rulers to form a Sunni-Shi'ite alliance between the two nations.
Writing in a U.S. magazine earlier this month, Natsios says Sudan is the only country that has formed what he calls "an enduring alliance with Iran based on a shared Islamist ideology."
Several specialists told VOA that Khartoum and Tehran developed an intelligence partnership in the 1990s, with Sudanese agents going to Tehran for training and Iranian agents using Sudan as an African hub.
Magdi El Gizouli, a Germany-based Sudan researcher with the Rift Valley Institute, says Sudanese admiration for Iran's Islamist system is no longer as important to the alliance as it was before.
"To prove that, you only need to think about the continuous intelligence cooperation between Sudan and the United States -- a development that started after the 9/11 [terrorist attacks] and continues until today," he says.
Sudan's need for weapons
Gizouli says Sudan wants Iranian arms because it is dealing with insurgencies on several fronts.
Rebels have been battling the Khartoum government in Sudan's southern provinces of South Kordofan and Blue Nile since last year. Khartoum also has been fighting rebels in the western region of Darfur since 2003.
Gizouli says arms embargoes on Sudan implemented by Western powers also have forced Sudanese authorities to seek alternative sources of weapons.
"They have customized versions of Iranian missiles, Russian missiles and Chinese missiles, whatever they could lay their hands on," he says. "So any country that is ready to deliver technology to Sudan, Sudan will jump at the opportunity."
The United Nations Security Council imposed an arms embargo on warring parties in parts of Sudan in 2004. But, it has permitted countries to supply weapons to Sudan provided they receive guarantees the arms will not be used to commit atrocities.
Gabe Joselow in Nairobi contributed to this report