At least eight people were killed when riot police clashed with protestors in two Sudanese states on Thursday, local authorities have said.

Six people died in eastern Al-Qadarif city and two others in northern Atbara, River Nile State.

Thousands countrywide have been protesting against the government's decision to increase the price of bread from one Sudanese pound to three (from about two to six US cents).

The angry protestors have also torched the ruling National Congress Party (NCP's) offices in two other cities.

A state of emergency has been declared in Al-Qadarif and River Nile State with government warning citizens against damaging property.

At least 20 protesters have also been arrested.

Opposition parties National Uma Party, Sudanese Congress Party, and Sudanese Communist Party, have supported the protests and called for the overthrow of President Omar al-Bashir's government.

The government has partially shut down the internet and blocked social media sites including Facebook and WhatsApp.

Bread shortage has hit Sudan's cities for almost a month, including the capital Khartoum.

The cost of basic commodities has more than doubled with an inflation rate of 69 percent.

The Sudanese pound has also plunged in value.