Gaborone - Botswana on Monday said it will lobby southern African leaders for an audit of Zimbabwe's disputed elections, calling into question the fairness of President Robert Mugabe's victory.
Foreign affairs minister Phandu Skelemani said Botswana was concerned that Wednesday's vote had not measured up to Southern African Development Community (SADC) guidelines.
"Various incidents and circumstances were revealed that call into question whether the entire electoral process, and thus its final result, can be recognised as having been fair, transparent and credible," he said in rare African criticism of the vote.
Western nations have voiced serious doubts about Zimbabwe's election - slammed as "fraudulent" by the opposition - after it extended 89-year-old Mugabe's 33 years in power.
SADC said it was "free and peaceful" but stopped short at saying it was fair.
A dossier of irregularities witnessed by Botswana's 80 member observer team will be shared with SADC, the African Union and the international community.
The 15-member regional SADC will then be lobbied to approve an independent audit of the vote during its heads of state meeting later this month in Malawi.
"We need an audit to enable us to pronounce as to whether the elections meet the SADC guidelines," Skelemani told journalists.
Botswana's observers had spotted various incidents prior to the elections though the voting day was "free and peaceful", he said.
President Ian Khama is one of the few African leaders to openly criticise Mugabe.
In 2008, Harare's diamond rich neighbour refused to accept the veteran leader's re-election in chaotic polls.