Sudan's President Omar al-Bashir has ordered the release of all political prisoners held in the country, state news agency SUNA said on Tuesday.

The decision came in response to the calls from political parties and groups participating in the country's ongoing national dialogue to grant detainees the opportunity to engage in the country's political process, SUNA reported.

"President Omar al-Bashir on Tuesday issued a decree to release all political detainees held across the country," the official SUNA news agency reported, quoting a decree issued by Bashir.

The news agency did not specify how many political prisoners the decision would affect or the names of any of those set to be released.

Hundreds of opposition activists, leaders and protesters were arrested in January by security agents to curb demonstrations that erupted on the back of rising food prices, including bread.

The January arrests came after sporadic protests erupted in the capital Khartoum and some other towns of Sudan after the price of bread more than doubled.

Some activists were later freed but many remain in detention, including top opposition leaders Khaled Omar of Sudanese Congress Party and Mokhtar al-Khatib, head of Sudan Communist Party.

The United States and European embassies in Sudan had called for the release of all detainees, with Washington's mission in Khartoum saying that many were being held in "inhumane conditions".

Sudanese authorities had cracked down on protesters in a bid to prevent a repeat of deadly unrest that followed an earlier round of subsidy cuts in 2013.

At that time dozens of people were killed when security forces crushed demonstrations, rights groups say.