Sudan's President Omar al-Bashir appointed a first vice president and a new prime minister on Saturday, a day after declaring a state of emergency to counter the most sustained protests since he came to power 30 years ago in a military coup.

Mohamed Tahir Ayala, the former governor of Gezira state whom Bashir had previously touted as a potential successor as president, was appointed prime minister. Defence Minister Awad Mohamed Ahmed Ibn Auf became first vice president while retaining his defence portfolio.

Bashir declared a one-year nationwide state of emergency on Friday and set up a caretaker administration. He replaced all state governors with military officials.

Urging his opponents to join a "path of national reconciliation" and dialogue, he called on parliament to postpone constitutional amendments that would have allowed him to seek another term in 2020.

There are no signs that has calmed matters, with the National Consensus Forces, one of the main opposition groups, saying the state of emergency was aimed at countering a "popular revolution" and vowing to push ahead until he is toppled.

Defence Minister Ibn Auf previously served as the head of military intelligence.

Earlier this month, he became the second of several top officials to strike a conciliatory tone towards the protests, saying that young people caught up in the recent turmoil had "reasonable ambition".