Hundreds of Sudanese students on Monday threw rocks at riot police and were met with tear gas salvoes on the third consecutive days of protests over a doubling in bread prices, witnesses said.

They said police formed a cordon to force more than 300 marchers onto the campus of Khartoum University, the largest in Sudan, and continued to fire tear gas at students chanting, "No, no, no to price rises!"

A smaller number of protesters gathered in Kosti, Sudan's biggest Nile river port 350 km (217 miles) south of the capital, but were dispersed by baton-wielding police.

Street protests broke out across the sprawling northeastern African country after bread prices doubled following a government announcement late last month that it was eliminating subsidies in its 2018 budget.

A high school student was killed and six others wounded on Sunday in the southwestern city of Geneina. Authorities did not give a cause of death but said investigations were under way.

This month Sudan devalued its pound currency to 18 per U.S. dollar from 6.7 pounds to the dollar previously.

Amid the continuing unrest, the exchange rate on the black market hit about 29.5 pounds to the dollar on Monday, compared with 28 pounds to the dollar a day before.

State Minister of Interior Babkar Daqna denied that the demonstrations were in response to price rises and said that destructive protesters would be "dealt with forcefully", state news agency SUNA reported on Sunday.