The government was due to have handed over Savimbi's body to representatives of Unita, which is now an opposition party, so that he may be buried in his hometown on 1 June.
However, the handover did not happen - and both sides are now blaming each other.
Helena Savimbi, one of the rebel leader's daughters, told AFP news agency that the government was not respecting accords. "It's total confusion," she is quoted as saying.
The government has in turn accused Unita of failing to collect the body on Tuesday, as agreed.
Unita rebels, backed by the US and South Africa, fought Angola's MPLA for 27 years - one of the Cold War's longest conflicts.
Savimbi was killed in a battle with government forces in 2002, and buried in Angola's eastern Moxico province. His death led to a peace deal, and the eventual inclusion of the rebels in the political process.
As the main opposition party, Unita has been campaigning for Savimbi to receive proper funeral.
The exhumed body was due to have been handed over in Luena, the capital of Moxico province, on Tuesday.
But according to a Unita spokesman, Alcides Sakala Simoes, the government changed the plan "at the last minute", saying the handover would take place in "Kuito and finally Andulo" - both towns in central Angola.
"We don't know where the body is... they are trying to humiliate Unita," he told the AFP news agency. "This will not help the process of national reconstruction."
However, Minister of State Pedro Sebastiao dismissed the claim.
According to the state-run Angola Press agency, he said the body had been taken to Luena as arranged but as Unita had not been there for the handover, it had left at a military barracks for collection.