IOC Chairman Jacques Rogge in Beijing on 10 April 2008

IOC Chairman Jacques Rogge has spoken of "crisis"

Beijing has moved to reassure Olympic officials the troubled torch relay will now go smoothly, after being marred in three countries by anti-China protests.

The International Olympic Committee, which met Chinese officials in Beijing, said it hoped the relay could go ahead with more "cheers and smiles".

The Olympic flame is now in Argentina, where further protests are expected.

UN Secretary General Ban Ki-moon has told China he will not attend the opening ceremony in August.

At a news conference, IOC spokeswoman Giselle Davies said: "The [ Beijing] organising committee today did underline to us that they have taken steps to make sure that any future risk, if there is any, is mitigated.

Map of planned world torch relay route

"We're very confident and comfortable with that, and we do hope the torch relay can now progress with many more cheers and smiles and the kind of atmosphere that it deserves."

On Thursday, IOC president Jacques Rogge urged China to respect its "moral engagement" to improve human rights.

But Beijing told the IOC to keep politics out of the Games.

In Buenos Aires, several thousand police are braced to line the torch's planned 13km (eight mile) route through the Argentine capital.

Demonstrators in down town Buenos Aires on 10 April 2008

Next stop is Tanzania, where Nobel Peace Prize laureate Wangari Maathai has withdrawn from the relay citing concerns over human rights in China.

Record claim

The Olympic flame is being relayed through 20 countries before it arrives in Beijing for the opening ceremony.

The BBC's Quentin Sommerville in Beijing says China has predicted more world leaders will attend its Olympics than went to the last games in Athens.

But it is a promise which might prove difficult to fulfil, says our correspondent.

The UN said on Thursday its secretary general told China months ago he could not be at the opening ceremony because of scheduling issues.

British Prime Minister Gordon Brown and German Chancellor Angela Merkel have also said they will not be there, while French President Nicolas Sarkozy is mulling whether to go.

US President George W Bush is under pressure from White House hopefuls John McCain, Hillary Clinton and Barak Obama not to attend.

The relay disruption follows violent anti-Beijing protests in and around Tibet last month which were suppressed by a heavy security presence.

On Thursday it emerged that China had refused permission for the UN's High Commissioner for Human Rights, Louise Arbour, to visit Tibet.

Activists are also protesting at China's links with Sudan, which is accused of genocide in Darfur.

Torch-bearers have been protected by police and Chinese guards in blue track-suits.

In Paris, the torch had to be extinguished three times amid safety concerns, while in London there were 37 arrests.

The US stage of the torch relay in San Francisco on Wednesday passed off amid confusion and tight security.

On Thursday, China said it had foiled terror plots by Muslim separatists in north-western Xinjiang province to disrupt the Games.

The Dalai Lama - who many Tibetans regard as their spiritual leader - said China deserved the Games but activists were entitled to non-violent protests.

Beijing says Tibet is an integral part of China and what happens there is an internal matter.