Two Iranian warships docked for refuelling on Monday in Port Sudan, across the Red Sea from Iran's regional rival Saudi Arabia.
Sudan's army spokesman Sawarmi Khaled Saad said the warships, one of them a navy supply ship, had arrived in Port Sudan, where civilians could tour the vessels during their port call.
Naval vessels from Iran have periodically stopped in Port Sudan for what Khartoum describes as normal port calls.
The coastal city lies about 250 kilometres (155 miles) across the Red Sea from Saudi Arabia, which has long been wary of Iran's regional ambitions.
In March, a Western diplomat said strained political relations between Riyadh and Khartoum over Iran could have been a factor in a decision by Saudi banks to stop dealing with Sudan.
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Khartoum also has close ties with Qatar, which is perceived as supporting the Egypt-based Muslim Brotherhood, towards which Saudi Arabia and other Gulf monarchies have long been hostile.
Relations between Sudan and Saudi Arabia are "zero", a senior Sudanese opposition politician told AFP last month.
But Ibrahim Ghandour, an aide to President Omar al-Bashir, said in a March interview that there is "nothing peculiar" in Sudan's relations with Iran, insisting they had not affected ties with other countries, including Saudi Arabia, which remains a leading investor.
On Monday Sudan's foreign ministry described relations with the Gulf as "stable" and said ties with Saudi Arabia are based on "mutual respect," in a report to parliament, the official SUNA news agency said.
The SUNA report did not mention Iran.