“We are preparing to send the black box,” to Russia, Abdelhafiz Abdelrahim, spokesman for the Sudan Civil Aviation Authority, told AFP.
Local investigators and their Russian colleagues are coordinating the transfer of the box to an Antonov laboratory in Moscow, he said.
The so-called black box contains flight data and cockpit voice recordings.
The crashed aircraft was an Antonov AN-26, a type which the Antonov company website says was made in Kiev, in the former Soviet Union.
All six crew and 26 passengers died on August 19 when the plane went down on a hill near Talodi, a town in war-torn South Kordofan state.
The delegation, led by Guidance and Endowments Minister Ghazi Al-Saddiq, was flying from Khartoum for a ceremony to mark the Eid al-Fitr holiday which ends the Muslim fasting month of Ramadan.
The airplane was operated by Alfa Airlines, a Sudanese passenger and cargo charter firm.
Managers of the carrier said that although the plane was about 35 years old it had passed mandatory maintenance checks and carried safety gear including weather radar, a Traffic Collision Avoidance System and Enhanced Ground Proximity Warning System.
The Russian captain of the plane was among those killed.
Air accidents are common in Sudan, which has an ageing fleet of aircraft.
Europe bans all Sudanese airlines, including Alfa, for safety reasons.
Ethnic minority rebels in South Kordofan have been battling government troops since June last year but said they had nothing to do with the crash, which happened in a government-controlled area.