The fast-spreading and heavily mutated Omicron variant has rapidly become the dominant variant worldwide since it was first detected in southern Africa 10 weeks ago.

The former mayor of Lisbon took the reins in 2015 following a ballot in which his Socialists finished second behind a centre-right coalition that had overseen a harsh EU-imposed austerity program.

Relieved party chiefs thanked 80-year-old Mattarella for agreeing to remain, but the failed attempts to replace him during seven rounds of balloting have left deep scars, with potentially dangerous repercussions for political stability.

"Secretary Blinken ... conveyed that de-escalation and diplomacy are the responsible way forward," department spokesman Ned Price said in a statement.

The Kremlin's point man on Ukraine was due to meet officials from France, Germany and Ukraine for "Normandy format" talks in Paris against the backdrop of a Russian military buildup near Ukraine that has sparked fears of an invasion.

"Over 21 million new cases were reported, representing the highest number of weekly cases recorded since the beginning of the pandemic," the World Health Organization said in its weekly epidemiological coronavirus update.

Allegations that a string of parties were held at Downing Street while the rest of the country abided by the rules she set have shaken Johnson's government, prompting the worst crisis of his premiership and calls for him to quit.

"The COVID-19 pandemic is now entering its third year and we are at a critical juncture," said Tedros Adhanom Ghebreyesus at a press conference alongside Germany's development minister Svenja Schulze.

President Joko “Jokowi” Widodo addressed the Davos forum as this year’s host of the Group of 20, with the idea of forming a new multilateral institution to anticipate global crises modeled after the International Monetary Fund.

As backroom negotiations hit fever pitch this week, the brashest campaigner has been billionaire Silvio Berlusconi, whose charm offensive has included bragging about his raunchy "bunga bunga" parties.

"Our minimal presence in Kabul must not in any way be seen as recognition" of the Taliban government there," EU foreign affairs spokesman Peter Stano said in a statement. 

The talks between Secretary of State Antony Blinken and Foreign Minister Sergei Lavrov come just 11 days after their deputies met in Geneva and agreed to preserve dialogue amid Russia's build-up of tens of thousands of troops on Ukraine's border.

Some younger lawmakers have spearheaded attempts to unseat Johnson, but it was an attack by one of the party's longest-serving Conservatives that prompted gasps when he told the prime minister in parliament "In the name of God, go."

Biden said he did not believe that President Vladimir Putin wants a war, but said the Russian leader has created a situation that is proving extremely difficult to defuse -- and that could easily "get out of hand" in the region.

Europe's biggest economy recorded 112,323 new infections over the past 24 hours and 239 fatalities, the Robert Koch Institute said.

Blinken, who will meet Wednesday in Kyiv with President Volodymyr Zelensky, will "reinforce the United States' commitment to Ukraine's sovereignty and territorial integrity," State Department spokesman Ned Price said.

"It is deeply regrettable that this took place at a time of national mourning and Number 10 (Downing Street) has apologised to the palace," Johnson's spokesman told reporters.

Kazakh President Kassym-Jomart Tokayev asked for assistance from the Collective Security Treaty Organisation (CSTO) last week as violence gripped half of the country while he dismissed some of his senior security officials who were later charged with treason.

Opposition leader Keir Starmer and even members of his own party have called for him to resign after he admitted to attending the event in Downing Street's garden during Britain's first lockdown in May 2020, and there was little sympathy on the streets of the British capital.

The WHO said the global surge in cases was being driven by Omicron, which is more transmissible than the previously dominant Delta variant.

"I know the rage they feel with me over the government I lead when they think that in Downing Street itself the rules are not being properly followed by the people who make the rules," an ashen-faced Johnson told parliament.

"A contingent of CSTO peacekeeping forces has been sent to Kazakhstan -- and I want to emphasize this -- for a limited time period," Putin said during a meeting of leaders from ex-Soviet countries, during which he added that Kazakhstan had been targeted by "international terrorism" and vowed that Russia would not allow "revolutions" in the region. 

Russian Deputy Foreign Minister Sergei Ryabkov said over the weekend it was entirely possible the diplomacy could end after a single meeting, and even US Secretary of State Antony Blinken played down expectations for the high-stakes talks.

Security forces appeared to have reclaimed the streets of the country's main city on Friday, a day after Russian paratroopers arrived to help quash the uprising.

Tokayev told Putin that the situation in Kazakhstan was stabilizing and thanked him for the deployment of a Russian-led military bloc to Kazakhstan to curb the worst violence the Central Asian country has witnessed since the collapse of the Soviet Union.

Blinken on Friday challenged Russia's justification for sending forces into Kazakhstan after days of violent unrest in the Central Asian country.

Some 313 deaths within 28 days of a positive COVID-19 test were reported on Saturday, taking the total number of fatalities on this measure to 150,057.

Mukhtar Ablyazov, a former energy minister and bank chairman wanted in his home country on a range of charges, in an interview with AFP also described a Russian-led military intervention as an "occupation" and urged Kazakhs to stand up to the foreign forces.

Opponents including rivals in the 2022 presidential elections accused Macron of overstepping the line with the language of his comments, while the furore they caused prompted a new delay in the passing of legislation aimed at tightening France's COVID rules.

Prime Minister Boris Johnson resisted imposing stringent lockdown measures in England ahead of New Year as Omicron fuelled a spike in cases to record highs.