"We have to help them so that the coalition government works," Motlanthe said in an interview with the South African Broadcasting Corporation, referring to power-sharing between President Robert Mugabe and prime minister-designate Morgan Tsvangirai.
It "may be practical for them to enter into an arrangment with the Reserve Bank here and allow the rand to become the common currency," he added, without fleshing out his suggestion.
Motlanthe also currently serves as president of the Southern African Development Community, which is mediating the crisis.
Prices in Zimbabwe rose by 231-million percent in July — the last time official inflation figures were made public. However, anaylsts say inflation in Zimbabwe actually stands at several billion percent.
The Zimbabwean dollar has been repeatedly devalued and restrictions on the use of foreign currencies — including the US dollar, the euro and the rand — have been lifted by Harare.
Zimbabwe is also struggling to fend off a deepening humanitarian crisis amid a cholera epidemic blamed on collapsed infrastructure and a desperate need of food aid, according to international agencies.
Motlanthe also urged the international community to help the new power-sharing government, due to be installed this week, after the African Union called for sanctions against Mugabe and his aides to be lifted.
Meanwhile, Motlanthe said Mugabe and Tsvangirai appear to be "getting along" as the dawn of their new unity government nears.
"They seem to be getting along fairly well," Motlanthe said on Sunday.
"We are optimistic that they can at least manage a transition period until they are ready to hold fresh elections."
The power-sharing pact aims to end almost a year of intense political turmoil following disputed March 2008 elections, in which Tsvangirai’s party seized a parliamentary majority in the first round.
"Whether they like it or not, or whether they like each other or not, they are bound to work together if anything is to be passed by that assembly and if the country iself is to pull itself out of poverty and disintegration of its infrastructure," said Motlanthe.
Political analysts have said they doubt a union government will work, citing a deeply-rooted lack of confidence between the two men.
Mugabe has frequently referred to his adversary as a Western "lackey" or "puppet," while Tsvangirai has accused Mugabe, in power since 1980, of human rights violations. – AFP