The Zajedno (Together) coalition, whose street protests forced the government to recognise its election victories in Serbia's main towns, has threatened to resume demonstrations unless media controls are relaxed by 9 March.
Zajedno leaders believe access to the state media will be crucial to their chances of beating the ruling Socialist Party (SPS) in parliamentary and presidential elections this year.
The warning to foreign journalists by Information Minister Radmila Milentijevic suggests the government will not give ground without a fight.
She told the pro-government daily Politika: "We must especially hold [foreign journalists] responsible for what they write. This means that if they write something which is not factually correct, we should react and demand the untruth be corrected."
Ms Milentijevic, a newly appointed loyalist to President Slobodan Milosevic, added: "In view of the force and influence the media exert on the shaping of public opinion and government policy, their responsibility is exceptional." In its last crackdown on the foreign media in 1994, at the height of the war in Bosnia, Serbia refused to renew the accreditations of almost 20 foreign journalists.
Although Serbia has no censorship, the main broadcast and print media are under strict state control. Independent radios have limited range and the government rations the supply of newsprint to independent newspapers and magazines.
The limited reporting by state television on three months of Zajedno and student demonstrations against SPS attempts to rig the local election results was hostile to the opposition.
The opposition called off demonstrations on Saturday but set a new deadline. A Zajedno leader, Zoran Djindjic, told supporters: "Let us give them a chance to show an intention to free the media and, if they fail to do that by 9 March, what else can we do but go out into the streets again?"
Belgrade students who have also held daily protests said they would continue their demonstrations until the government sacked the university rector and prosecuted those responsible for annulling the local election results.