Direct pre-publication censorship was reintroduced for two daily papers last month and on Saturday night four others also complained they were visited by Sudanese security forces who removed many pages of content.
"We will suspend our newspaper for a week in protest at the pre-(publication) censorship," said Faiz Al-Silaik, acting editor in chief of the Ajras Al-Huriya paper, aligned to the former southern rebel Sudan People's Liberation Movement who signed a 2005 north-south peace deal with Khartoum and formed a coalition government.
Ajras Al-Huriya was unable to go to press on Sunday for the third day in a row and the opposition Al-Meydan, aligned to the Communist Party, was not allowed to print.
"They went to the printing press...and they told the press not to print the paper," said managing editor Mohamed el-Fatih from Al-Meydan. "The main news they were unhappy about seemed to be the doctors' strike."
Journalists from six independent or opposition papers told Reuters they were visited and directly censored by the security forces late on Saturday night.
Other papers said they were called and told not to write about specific news including the strike by doctors over pay and working conditions and the International Criminal Court, unless it was from a government source.
The ICC issued an arrest warrant for President Omar Hassan Al-Bashir last year for war crimes during a brutal counter-insurgency campaign in Sudan's western Darfur region, charges he rejects.
Sudan's security forces were not immediately available for comment.
April elections, marked by opposition boycotts and allegations of widespread fraud, returned Bashir's ruling National Congress Party to power in the north with a massive majority. Since then, it has cracked down on political and press freedoms.
Sudan's press opened up after the 2005 north-south peace deal. But media freedom suffered as a result of rising tensions with the ICC and Darfur's separate humanitarian crisis, triggered after 2 million fled their homes during the fighting.
South Sudan will vote on a key referendum on secession in January. Journalists in the semi-autonomous south have also been harassed, with many arrested or detained by the authorities.
