Six African leaders are to travel to Russia and Ukraine in a bid to find an end to the conflict, South Africa's president has announced.

Cyril Ramaphosa said he had held separate phone calls over the weekend with his Russian and Ukrainian counterparts.

Both Russia's Vladimir Putin and Ukrainian leader Volodymyr Zelensky had agreed to the plan, he said.

"Principal to our discussions are efforts to find a peaceful resolution to the devastating conflict in the Ukraine, its cost in human lives and impact on the African continent," Mr Ramaphosa said.

"I presented the initiative on behalf of African heads of state from Zambia, Senegal, Congo, Uganda, Egypt and South Africa."

It is not clear whether he was referring to Congo-Brazzaville or the Democratic Republic of Congo.

"The two leaders agreed to receive the mission and the African heads of state, in both Moscow and Kyiv," the South Africa leader said, adding that the UN chief had been briefed and welcomed the African initiative.

Mr Ramphosa's comments, made in Cape Town during a visit by Singapore's Prime Minister Lee Hsien Loong, come as senior South African military officers are visiting Russia.

The South African leader has reiterated that South Africa will not take sides over the war in Ukraine.

This follows the diplomatic row that erupted last week when the US ambassador to South Africa accused the country of secretly providing arms and ammunition to Russia.

Mr Ramaphosa has agreed to investigate the claim but says there is no concrete evidence to support the allegations.