Sudan has ordered Iran to close its cultural centres and given their managers 72 hours to leave the country, officials have said, as a diplomatic row threatens normally close relations.

"Sudanese authorities summoned the Iranian charge d'affaires in Khartoum and informed him of the decision to close the three cultural centres and to give the diplomats who ran them 72 hours to leave the country," the AFP news agency quoting an unnamed official said on Tuesday.

Sudanese media speculated that the expulsions were linked to government concerns that Iranian officials were promoting their Shia brand of Islam in the largely Sunni country, according to the Reuters news agency.

The Iranian cultural centre and its branches had exceeded their mandates and "become a threat to intellectual and social security," said a foreign ministry statement.

Regional rivalries

Khartoum has maintained generally close relations with Tehran, whose ships have made a number of port calls in Port Sudan this year.

Iran is also reportedly a significant arms supplier to Sudan and the two governments are both backers of Hamas, although Sudan has denied Israeli accusations that it has acted as a conduit for Iranian arms deliveries to the Palestinian group.

Sudan turned down an Iranian offer to set up air defences on its Red Sea coast after a 2012 air strike Khartoum blamed on Israel, fearing it would upset Tehran's regional rival, the Sunni superpower Saudi Arabia, Sudan's foreign minister said in May.

A Sudanese analyst told AFP that the move by Khartoum might be in response to pressure from Riyadh, which put enormous strain on the Sudanese economy earlier this year by denying it access to the Saudi banking system.