Sudan's links to Iran came under scrutiny on Thursday after Khartoum accused Israel of being behind a deadly missile strike on a military factory in the heart of the capital.

The cabinet met in urgent session late on Wednesday after the government said evidence pointed to Israeli involvement in the alleged attack at around midnight on Tuesday on the Yarmouk military manufacturing facility in southern Khartoum.

Sudan accused the Jewish state of a similar raid 18 months ago.

Analysts, however, said they had not ruled out an accidental cause for the latest blast.

Israeli officials have expressed concern about arms smuggling through Sudan and have long accused Khartoum of serving as a base of support for militants from the Islamist Hamas movement that rules the Gaza Strip.

Israel refused all comment on Khartoum's allegations, but Amos Gilad, a top Israeli defence official, called Sudan "a dangerous terrorist state."

Gilad, director of policy and political-military affairs at the defence ministry, refused to reply directly when asked whether Israel was involved in the attack, which Sudan said was conducted by four radar-evading aircraft.

"The regime is supported by Iran and it serves as a route for the transfer, via Egyptian territory, of Iranian weapons to Hamas and Islamic Jihad terrorists," he told his country's army radio on Thursday.

"Sudanese President Omar al-Bashir is regarded a war criminal."

Bashir is wanted by the International Criminal Court for alleged crimes against humanity, war crimes and genocide in Sudan's Darfur region where a rebellion began in 2003.

His cabinet issued no statement after Wednesday's late meeting, where Bashir joined anti-Israel protesters in chanting "Allahu akbar" ("God is greatest").

About 300 demonstrators denounced the United States and carried banners calling for Israel to be wiped off the earth.

Jonah Leff, of Small Arms Survey, a Swiss-based independent research project, said the project has documented the presence of a drone, landmines and other Iranian weapons in Sudan but he thinks they were acquired directly from Iran rather than being locally manufactured.

"There's a lot of speculation that Iran has provided technical assistance to the Sudanese for their weapons manufacturing but I haven't been able to confirm that they're producing any Iranian weapons," he said.

On a visit to Tehran last August, Bashir described the relationship between Sudan and Iran as "deeply rooted."

Leff identified Yarmouk as part of Sudan's Military Industry Corporation, which claims to produce a variety of weapons from pistols to battle tanks.

"They're highly secretive... It's hard to know what exactly they're producing and what is propaganda," Leff said.

Information Minister Ahmed Bilal Osman told reporters on Wednesday that the factory made "traditional weapons."

Nearby residents told AFP an aircraft or missile had flown overhead shortly before the area exploded in flames, sending bursts of white light into the night sky.

Sudan called on the UN Security Council to condemn Israel for what its envoy, Daffa-Alla Elhag Ali Osman, called "a blatant violation of the concept of peace and security" and the UN charter.

On Wednesday, before officials accused Israel, the governor of Khartoum state Abdul Rahman Al-Khider dismissed speculation that "other reasons" caused the explosion, which he said happened in a storeroom.

A diplomatic source said "the human factor" -- a possible accidental cause -- should not be ruled out, although Sudanese officials are taking allegations of Israeli involvement seriously.

Leff said it is just as likely that the Sudanese are blaming Israel to avoid embarrassment after an accidental blast.

"I wouldn't expect Sudan to have all the necessary safeguards in place to protect its ammunition depots," which is a common deficiency in Africa, he said.

In April last year, Sudan said it had irrefutable evidence that Israeli attack helicopters carried out a strike on a car south of Port Sudan.

That incident mirrored a similar attack by foreign aircraft on a truck convoy reportedly laden with weapons in eastern Sudan in January 2009.