Sudanese security agents seized all copies of four independent newspapers on Tuesday after they reported on a three-day strike called by the opposition over fuel subsidy cuts, staff said.
Discontent has been simmering for weeks over the subsidy cuts, which have led to a sharp rise in the cost of other goods, and opposition groups called for a nationwide strike from Sunday.
The strike call came despite the arrest of at least a dozen opposition leaders as the authorities sought to prevent any repetition of deadly unrest that followed a previous round of subsidy cuts in 2013.
Members of the powerful National Intelligence and Security Service confiscated copies of Al-Tayar, Al-Jadida, Al-Ayyam and Al-Youm Al-Tali newspapers overnight without giving a reason, staff said.
"At 2:00 am today (2300 GMT Monday) an NISS officer came and ordered our printer to stop printing," said Al-Tayyar editor-in-chief Osman Mirgani.
"He confiscated the entire print run without giving any reason."
Al-Tayyar, which has faced similar action in the past, had given the strike extensive coverage.
"Exceptional Day in Khartoum," it headlined on its front page on Monday.
Al-Jadida editor Ashraf Abdelaziz said the paper's managers were considering whether to try to publish on Wednesday after its Tuesday edition was confiscated.
"It's a big financial loss when copies are confiscated as we have to pay the printer and also lose advertisement revenues," he said.
The streets of Khartoum were deserted on Sunday morning -- the start of the working week in Sudan -- as some bus drivers stopped work and many people stayed at home for fear of clashes between strikers and the security forces.
But on Monday and Tuesday bus services resumed and life began to return to normal, AFP correspondents reported.
A private TV channel has also been ordered off the air.
Authorities halted broadcasts by the Omdurman Channel on Sunday, accusing it of operating without a licence, a charge its owner denied.
Media in Sudan are frequently targeted for their reporting. The country regularly ranks near the bottom of international press freedom rankings.
There have been sporadic protests for weeks over the fuel subsidy cuts and the authorities have been desperate to stop them gaining momentum.
Much larger protests in 2013 were put down only with the use of deadly force which drew international condemnation.