BBC's Jonah Fisher reports
from Khartoum today on Sudanese security forces firing teargas on crowds in Khartoum. Excerpt:
On the face of it, this protest was about a recent rise in fuel prices.
But it is also the frontline of an increasingly bitter struggle between the Khartoum government and an alliance of opposition political parties.
Several demonstrations in the last few weeks have been banned and then violently disrupted.
What was once about fuel has turned into a question of freedom of expression.
Note, the report points out that Sudan's police rarely permit opposition protests.