Seven people have been killed in and around the Sudanese capital as protests over the government's lifting of fuel subsidies entered the third day, witnesses have said.

The protesters were killed on Wednesday in clashes with security forces in Khartoum and its sister city Omdurman, AFP reported.

Security forces fired tear gas to disperse the demonstrators.

The demonstrators burned vehicles in a hotel car park near Khartoum’s international airport, and a petrol station in the area was also set alight.

On Tuesday, protesters stormed and torched the offices of the ruling National Congress Party in Omdurman.

The protests, which have now cost the lives of 10 people, began on Monday when the government lifted fuel subsidies to raise revenue.

Two people had already been killed in riots in the Khartoum area, police and the family of one of the victims said, and a third person was killed south of the capital on Monday.

Sudan’s Education Ministry announced that schools in the capital would remain closed until the end of the month.

Sudan lost billions of dollars in oil revenues after South Sudan gained independence two years ago, taking with it some 75 percent of crude production of the formerly united country.

Sudan has been plagued by running inflation and a weakening currency since then.