Sixteen people accused in Sudan of attacks on police stations during protests sparked by high fuel prices were arrested far from the crime scenes, witnesses told a trial on Tuesday.

The 16 are among hundreds detained in a crackdown after the government cut fuel subsidies on 23 September, sending thousands into the streets to protest in the worst urban unrest of President Omar Al-Bashir's 24-year rule.

Thirty-five people initially appeared before a judge in Khartoum's impoverished Haj Yousef district on charges of vandalism and causing a disturbance.

A judge acquitted 19 for lack of evidence but 16 others, including eight youths under the age of 17, were still on trial, said Mutasim Al-Haj, one of their lawyers.

Twelve witnesses testified for the defence on Tuesday, he said.

"They said these people were not arrested during a demonstration. Nor were they arrested during the stoning or burning of police stations," Haj said.

They were picked up "far away" from the alleged crime scenes, according to defence testimony, the lawyer added.

A judge is expected to give his verdict on Thursday after further defence evidence, Haj said.

Rights groups say political activists and opposition party members are among those rounded up after the demonstrations.

Security forces were believed to have killed more than 200 protesters, many of whom were shot in the head or chest, Amnesty International said.

Authorities have reported 34 deaths from the unrest.

The government said it had to intervene when crowds turned violent, attacking petrol stations and police.