Uganda's presidential spokesperson Onapito Ekomoloit said Kiir, who concluded a one day tour here on Wednesday, was "satisfied with the progress of the investigation".
Kiir led a 13-man delegation to the east African nation and held talks with President Yoweri Museveni in his first visit to Uganda since he assumed the seat of vice-president last month.
An international team is currently probing factors that led to the July 30 accident in which the Ugandan presidential helicopter that was carrying Garang crashed, killing a total of 14 people.
Museveni and Kiir "also discussed the operation against the Lord's Resistance Army (LRA) and agreed that they should have joint operations to get him from beyond the red line where he is hiding now," Ekomoloit told AFP by phone.
Last month, Kiir issued a stern warning to the LRA rebels to leave their hideout in southern Sudan jungles and urged Kampala to press forward with the stalled peace process.
Khartoum and Kampala in 2002 signed a deal allowing the Ugandan army to conduct raids in parts of remote Sudan following repeated complaints that Khartoum was harbouring the notoriously brutal LRA.
Despite several raids, the Ugandan army has failed to flush out the insurgents, who have been fighting since 1988, from southern Sudan.
Museveni, who supported Kiir's Sudan People Liberation Movement during its 21-years struggle against successive Islamic government in Khartoum, urged Kiir to stick the January peace deal that ended Africa's longest-running civil war.
"The president urged the SPLA to continue with the peace pact that was signed between them and the Sudanese government," said Ekomoloit. - Sapa-AFP