Some have called him an oil dictator who tortures his political opponents; others have hailed him as liberator of the poor. But today Hugo Chávez, president of Venezuela, is having lunch with mayor Ken Livingstone.

City Hall has been closed for the day while London's mayor hosts the Latin American strongman on the London leg of his European tour.

On Chávez's last visit to Britain in 1998 - shortly after being elected as president - he had tea with the Queen and met prime minister Tony Blair. But this time there will be no such thing: Downing Street has called his very public two-day stopover "private".

Chávez, who has since survived a coup, an election and a recall referendum, has become the face of global anti-Americanism.

His "Bolivarian Revolution" to combat social ills at home and oppose US president George W. Bush abroad has earned him more international headlines than any Latin American leader since Eva Peron.

Yesterday in Camden, north London, he addressed an 800-strong crowd for three-and-a-half hours after arriving nearly 90 minutes late.

The audience included the model-turned-activist Bianca Jagger, the Old Labour MP Jeremy Corbyn and millions who watched the live broadcast on Allo Presidente, his television show back home.

The mayor, whom Chávez called his "amigo", introduced the Venezuelan leader as the world's main figure capable to take on "the gangster regime" in Washington.

"Those who a decade ago said that socialism was dead, see it now very much alive in Venezuela," said Livingstone - also known as "Red Ken". The march against capitalism was now too strong for America to withstand, he added.

Chávez's marathon speech included a mother's day message to his mum, but no reference to Bush (whom he has previously slated as the "main ally of Hitler") or Blair (Bush's "imperialist pawn").

He did, however, call Washington "the greatest threat to this planet" and its war in Iraq "the Vietnam of the 21st century".

"The US empire doesn't know what to do in Iraq," Chávez said. "The political system hasn't worked. There's no government in the country and they do not know how to get out."

The consequences of an attack on Iran would be much worse, he added. "Imagine they launch this attack on Iran. They've got it planned. If the US attack Iran, people in England who drive cars will have to park them. Oil will be $100 a barrel."

Chávez's tour through Europe included audiences with the pope and EU leaders. On Monday afternoon he was scheduled to meet a number of MPs at parliament.

In a statement, the mayor said he was "delighted" to welcome Chávez. "He has introduced the first effective health service into Venezuela, commenced a huge literacy programme, and is paying for 250,000 people to have eye operations to cure them of blindness - a record any politician would be proud of."

But others were less than impressed. Brian Coleman, chair of the London Assembly, said it was "outrageous and incompetent" of the mayor to bar all external meetings at City Hall without warning to host the Venezuelan president.