CAIRO- Sudanese security forces fired tear gas at hundreds of protesters in the capital Khartoum and across the river Nile in Omdurman on Sunday, a Reuters witness said.

About a thousand protesters were confronted by forces in military uniform in Omdurman as President Omar al-Bashir swore in new officials after he dissolved the central and state governments on Friday.

Hundreds demonstrated in the Burri neighbourhood of Khartoum, where they blocked a main road, set fire to car tyres and chanted "Freedom! Freedom!".

Pillars of smoke could be seen rising over the area, where police fired heavy volumes of tear gas, the Reuters witness said.

Bashir appointed Mustafa Youssef to replace Moatazz Moussa as finance minister on Sunday, a presidential statement said.

Bashir, facing the country's biggest protests since he came to power 30 years ago, wore military uniform as he swore in a new first vice president, prime minister and governors of Sudanese states.

Mustafa Youssef was appointed to replace Moatazz Moussa as finance minister on Sunday, a presidential statement said.

Moussa had been both prime minister and finance minister, but has lost both positions within two days. Bashir on Saturday appointed Mohamed Tahir Ayala as prime minister.

Ayala, the governor of Gezira state, has been touted by Bashir as a potential successor as president. urn:newsml:reuters.com:*:nL5N20I0G5

Defence Minister Awad Mohamed Ahmed Ibn Auf, an ex-military intelligence chief, became first vice president, while retaining his defence portfolio. Bashir also kept in place his justice and foreign ministers.

Bashir had declared a one-year nationwide state of emergency on Friday and replaced all state governors with military officials. At their swearing in on Sunday, the new governors and Ibn Auf also wore military uniform.

Bashir on Friday also called on parliament to postpone constitutional amendments that would allow him to seek another term in a 2020 presidential election.

(Reporting by Khalid Abdelaziz Writing by Amina Ismail and Yousef Saba Editing by David Goodman) ((Yousef.Saba@thomsonreuters.com; +201222184730))