The president will also establish a national commission on Monday with Garang's Sudan People's Liberation Movement (SPLM) to oversee a technical committee already gathering evidence, said Civil Aviation Minister Ali Tamim Fartak.
"We have requested a visa for the committee to go to Uganda to collect information about the plane, the refuelling, the maintenance record of the plane, the black box and the voice box," Fartak told Reuters.
Garang was travelling on Ugandan President Yoweri Museveni's helicopter back to southern Sudan after a meeting with him on July 30 when it disappeared from radar screens.
The helicopter flew into a cliff face near an SPLM stronghold in the south, killing all 14 people on board.
Museveni has said he did not rule out the possibility the crash was not an accident. Garang was buried on Saturday in a state funeral in the southern town of Juba.
Garang signed a peace deal with the government in January ending Africa's longest civil war in the south.
Just 3 weeks before his death he returned in triumph to Khartoum to take up the position of first vice president alongside his former enemies.
His death sparked the worst rioting in Khartoum in decades as 111 people were killed and more than 300 injured in 3 days.
Fartak said the government would welcome help with the investigation from any country or organisation. The United States has offered to send five experts.
"I have given them four weeks so that they can present their preliminary report," Fartak said. The technical committee, which has seven government experts and would be joined by an unspecified number of SPLM officials, began work on Aug. 1, he said.
Fartak said the SPLM were welcome to hold an independent investigation, but said any investigation should include the government as the crash occurred on Sudanese soil.
Many southerners suspect foul play and do not want government involvement in the investigation.
- Reuters - Thomson Reuters Foundation
- For more humanitarian news and analysis, please visit https://www.trust.org/alertnet