Sudanese security forces used stun grenades and tear gas on Monday to disperse crowds of protesters rallying in Khartoum on the fourth anniversary of the uprising that toppled former leader Omar al-Bashir, a Reuters reporter said.

The protests in the capital come two weeks after the military leaders who staged a coup last year signed an outline deal with political parties to relaunch a transition towards democratic elections with international support.

The deal faces major challenges, including limited public backing for the civilian signatories and the deferral of contentious issues including transitional justice and reform of the security forces, analysts say.

Demonstrators, who called for civilian rule and justice over deaths during past protests, gathered in their largest numbers for several months on Monday, marching to within about 1.5km (1 mile) of the presidential palace.

(With input from Reuters)