Security forces have fired tear gas at demonstrators in Sudan, as protests against President Omar al-Bashir enter their second month.
President Bashir on Sunday reiterated claims that foreign "agents" and Darfur region rebels are fomenting dissent.
Officials say 26 people have died in the protests, but rights groups say more than 40 have been killed.
Protests about Sudan's economic problems began in December but morphed into anger at Mr Bashir's 30-year rule.
In a speech south of the capital on Sunday, the president blamed "infiltrators" for the killings.
"There are some people among the protesters who are killing the demonstrators," he reportedly said.
Hundreds of demonstrators tried to march on parliament in capital Khartoum's twin city Omdurman on Sunday.
They sought to hand in a petition demanding President Bashir step down, and chanted "Freedom, peace and justice" - the movement's main slogan - and "Overthrow, overthrow" as they marched.
But police fired tear gas to halt their progress and reportedly chased down the protesters.
Reuters news agency says about 30 vehicles carrying security personnel in uniform and plain clothes descended on the area.
There were also protests reported in the Khartoum districts of Burri and Bahari, to the east and north of the capital respectively.
There were reports a child was also killed, but organisers apologised on Sunday for what they called a "false report".
Activists say government forces have fired live rounds and rounded up suspects.
Sarah Jackson, East Africa deputy director for human rights group Amnesty International, blamed security forces for an "unbridled killing spree" in a press release.