The two contenders in Ghana's presidential run-off Saturday accused each other of planning to rig the decisive round of voting even as outgoing President John Kufuor called for a peaceful poll.

The ruling New Patriotic Party (NPP) and the opposition New Democratic Congress (NDC) both alleged their rivals were out to steal Sunday's run-off through intimidation and fraud.

"There was a lot of tension around the country towards the run-off," Kufuor told reporters at the new presidential palace when he met US Assistant Secretary of State for African Affairs Jendayi Frazer.

"I am appealing to all Ghanaians... we should all keep cool, go and vote, as a peaceful exercise, as a legitimate exercise," he said.

The NPP's Nana Akufo-Addo and John Atta-Mills of the NDC will face off Sunday after neither emerged as outright winner on December 7.

"Whoever the majority of us would support to become president, I believe we should be ready to accept them, so we should stop fuelling the tensions. Whether it's president Akufo-Addo or president Mills we should be able to live with them for the next four years, its not do-or-die," said Kufuor.

Opposition candidate Atta-Mills told a news conference Saturday that his party had in recent days unearthed "startling revelations and confessions (to rig elections).

"There are certain developments since December 7, which if not checked could distract from the peace and stability that we all want and could also affect the electoral process," said Mills.

The NPP for its part accused the opposition of having embarked on a "disturbing... intimidation scheme.

"In the last two days, a most diabolical and devious leaflet which seeks to inflame tribal passions and incite ethnic tensions has been in circulation," the NPP said in a statement, adding that two party activists had been assaulted by presumed opposition supporters.

"As if threats, attacks and violence is not enough, the NDC, we are reliably informed, also plans to engage in massive fraud during tomorrow's voting," said the NPP.

Mills for his part said the NDC was concerned about reports of "'Macho men' recruited... to cause mayhem at polling stations."

Police chief Inspector general Patrick Acheampong said officers would uphold the law.

Commonwealth chief observer to Ghana, Valerie Amos said development in the country requires "inclusiveness and a continued commitment to democracy, transparency and accountability.

"It is very critical at this stage that political parties, their supporters and the general public avoid conflict and violence," she said.

Chief election observer for the West African regional bloc ECOWAS, former Nigerian leader General Yakubu Gowon, said even if the stakes are high "I am sure it is going to be a another successful election."

Gowon, who described the first round as having gone "exceptionally well" expressed the hope that the "next round would also be the same."