The announcement follows talks on Wednesday between Egyptian President Hosni Mubarak and Sudanese President Omar al-Bashir on his first visit to Cairo for six years.
After that meeting, President Bashir described relations with Egypt as "strategic" and praised President Mubarak's "swift" support for the "new reality" in his country.
He also said Sudan was seeking to improve relations with international funds and the outside world, and said that the recent misunderstandings between the two countries were now over.
Support for Islamists
Relations between the two nations, became strained after General Bashir's 1989 coup installed an Islamist government in Khartoum, and worsened after a 1995 assassination attempt on President Mubarak in Ethiopia that was blamed on Sudan.
Since then Egypt has only been represented by a charge d'affaires in Sudan, although Sudan kept an ambassador in Cairo.
Earlier this month, Egypt supported the Sudanese president's declaration of a state of emergency, which was precipitated by his rivalry with former parliamentary Speaker Hassan al-Turabi.
Since then, President Bashir has pledged to speed up negotiations with opposition groups and prepare for new elections.
Opposition leaders hope President Bashir's split with Mr Turabi, who was the main ideologue behind the country's Islamist government, may have brought the prospects of peace closer and signal a move away from hardline Islamist policies.
President Mubarak's government has been trying to forge a dialogue between Khartoum and the Sudanese opposition.