Sudan's national security and intelligence department said in a statement that the editor of the Al-Watan daily was given permission to resume publication immediately.
Al-Watan was closed down in December 2002, when the government accused it of defamation and said it was undermining Sudan's relations with other countries. Officials accused the paper of inciting sedition and undermining society for its interviews with opposition leaders and southern rebels.
Since then, the government in Khartoum has reached a peace deal with southern rebels, signed in January, ending a 21-year civil war.
The department said the paper was allowed to reopen because of the country's "political changes and the national challenges faced by our country, which require rallying up more energy for unifying the national ranks."
Al-Watan's editor, Sidhamed Khalifa, was quoted by the official Sudan Media Center as welcoming the decision