BEIJING, June 3 (Xinhua) -- Outrage over the death of unarmed African American George Floyd at the hands of police in Minneapolis has been growing across the United States, and now, beyond.

Floyd, 46, died after a white police officer knelt on his neck for almost nine minutes until he stopped breathing.

In a video footage, the victim was heard saying "I can't breathe" while three other police officers stood by.

The incident has triggered massive protests against racial discrimination and police abuse across the country, prompting U.S. mayors and governors to impose curfews in more than 40 cities, while thousands of people have been arrested so far.

United Nations Secretary-General Antonio Guterres has called for restraint from the authorities in responding to demonstrators, said his spokesman, Stephane Dujarric, adding that Guterres hopes to see peaceful protests in the United States over the death of Floyd.

The tragedy has also set off protests outside the United States. In neighboring Canada, protesters took to the streets in Montreal to denounce racial profiling and police brutality.

In Greece, hundreds of members of the youth wing of the Greek Communist party KKE protested peacefully on Monday outside the U.S. Embassy in Athens and the U.S. Consulate in the northern city of Thessaloniki.

Raising banners of "I can't breathe," protesters outside the U.S. embassy chanted slogans such as "No to a system giving birth to crises, wars, and racism."

"We join Greek people's voice with the voices of all people across the world against the barbarity ... We join our voice with the U.S. people who are giving a struggle these days for their rights, to be able to breathe," KKE General Secretary Dimitris Koutsoumbas said earlier.

In Britain, thousands of people gathered in London and Manchester to protest over the death of Floyd, despite an official ban of mass gatherings.

Chanting "no justice, no peace," the protesters gathered in London's landmark Trafalgar Square shortly after 1 p.m. before marching through Westminster to Downing Street.

From the French capital city of Paris to the Israeli city of Tel Aviv, and from the Dutch city of The Hague to the Australian city of Sydney, demonstrators have rallied to voice support and demand improvement in race relations.

The killing of Floyd has sparked diplomatic concern around the world.

Josep Borrell, the European Union (EU)'s foreign policy chief, reportedly described the incident as an "abuse of power."

"We here in Europe, like the people of the U.S., we are shocked and appalled by the death of George Floyd and I think that also societies must remain vigilant against the excess of use of force," Borrell, the EU's High Representative for Foreign Affairs and Security Policy, was quoted by the Guardian as saying.

"This is an abuse of power and this has to be denounced as we combat (it) in the States and everywhere. We support the right to peaceful protest and also we condemn violence and racism of any kind and, for sure, we call for a de-escalation of tensions," said Borrell.

Germany's Foreign Minister Heiko Maas said the anti-discrimination protests in the United States are "understandable and more than legitimate."

Chairperson of the African Union (AU) Commission Moussa Faki Mahamat called on authorities in the United States to intensify their efforts to "ensure the total elimination of all forms of discrimination based on race or ethnic origin."

"I strongly condemn the murder of George Floyd that occurred in the United States of America at the hands of law enforcement officers, and wishes to extend my deepest condolences to his family and loved ones," he said in a statement.

"The AU Commission firmly reaffirms and reiterates its rejection of the continuing discriminatory practices against Black citizens of the United States of America," he added.

Ghana's President Nana Akuffo-Addo condemned the killing on his official Facebook account, saying that "Black People, the world over, are shocked and distraught by the killing of an unarmed man, George Floyd, by a white police officer in the United States of America. It carried with it an all too painful familiarity, and an ugly reminder."

"We stand with our kith and kin in America in these difficult times, and we hope that the unfortunate, tragic death of George Floyd will inspire a lasting change in how America confronts head on the problems of hate and racism," said Akuffo-Addo.