LEADERS from around the world have condemned the terror attack at a Manchester music concert and offered their condolences to the victims.

German Chancellor Angela Merkel, newly elected French President Emmanuel Macron and European Commission President Jean-Claude Juncker were among the first to offer messages of solidarity with the UK, while Donald Trump described those behind the murders "as losers".

"I extend my deepest condolences to those so terribly injured in this terrorist attack and to the many killed and the families, so many families, of the victims," said the US President, speaking during a visit to Bethlehem, in the Palestinian West Bank.

"We stand in absolute solidarity with the people of the United Kingdom."

Trump said "many young, beautiful, innocent people" had been "murdered by the evil losers in life".

He added: "I won't call them 'monsters', because they would like that term. They would think that a great name.

"I will call them from now on 'losers', because that is what they are."

Trump said civilised societies should have "no tolerance" for continued bloodshed of this kind.

"The terrorists and extremists and those who give them aid and comfort must be driven out from our society forever," he said.

"This wicked ideology must be obliterated and I mean completely obliterated."

Merkel said she was following the news from Manchester "with sorrow and horror" and offered her "deep sympathy" to all those affected.

"It is incomprehensible that someone could make use of a joyful pop concert to bring death to so many people or inflict serious injury on them," she said.

"This apparent terrorist attack will only strengthen our determination to keep acting together with our British friends against those who plan and carry out such inhuman deeds.

"I assure people in Britain: Germany stands by your side."

Macron said: "My thoughts are with the British people, the victims and those close to them. We are fighting together against terrorism."

The Elysee Palace said Macron would be speaking with Theresa May by telephone about the ongoing investigation.

Juncker said: "It was with great sadness and profound shock that I learnt of the brutal attack that struck Manchester.

"It breaks my heart to think that, once again, terrorism has sought to instil fear where there should be joy, to sow division where young people and families should be coming together in celebration.

"I would like to convey my deepest sympathies to Prime Minister May and to the British people.

"Today we mourn with you. Tomorrow we will work side by side with you to fight back against those who seek to destroy our way of life.

"They underestimate ours and your resilience, these cowardly attacks will only strengthen our commitment to work together to defeat the perpetrators of such vile acts."

The President of the European Council, Donald Tusk, tweeted: "My heart is in Manchester this night. Our thoughts are with the victims."

Guy Verhofstadt, the European Parliament's chief Brexit negotiator, also posted a message on social media.

"A horrible & cowardly attack in #Manchester. Targeting our youth at a concert is a heinous crime but they will prove unity & hope always win,." he tweeted.

The Kremlin released a statement on behalf of Russian president Vladimir Putin, saying he had "expressed his condolences to the British prime minister following (the) Manchester bomb attack".

Australian prime minister Malcom Turnbull told the country's parliament the incident was a "brutal attack on young people everywhere".

He said: "This incident, this attack, is especially vile, especially criminal, especially horrific because it appears to have been deliberately directed at teenagers.

"This is an attack on innocents. Surely there is no crime more reprehensible than the murder of children.

"This is a direct and brutal attack on young people everywhere, on freedom everywhere."

Indian prime minister Narendra Modi tweeted: "Pained by the attack in Manchester. We strongly condemn it. Our thoughts are with the families of the deceased & prayers with the injured."

In Japan a government spokesman said: "If this is a terrorist attack, such abhorrent acts of terrorism cannot be justified for any reason, and Japan firmly condemns such an act of terrorism.

"I would like to express my heartfelt condolences to the victims and families of the deceased and my prayers to a swift recovery for the wounded. Japan stands in solidarity with the people of the UK."

Canadian prime minister Justin Trudeau tweeted: "Canadians are shocked by the news of the horrific attack in Manchester. Please keep the victims & their families in your thoughts."

US First Lady Melania Trump wrote on Twitter: "My thoughts and prayers to the families of #Manchester."

French prime minister Edouard Philippe said: "The most cowardly form of terrorism has struck once more, targeting, as it did in Paris more than a year ago, a concert venue, aimed specifically and knowingly at very young girls gathered together for a moment of celebration and joy.

"In the wake of this abominable crime, I would like to express my sadness, the solidarity of the French people and unwavering friendship to Mancunians and all British people."

Senior politicians in Ireland also expressed their sorrow in message of support.

President Michael D Higgins offered sympathies on behalf of Irish people and wrote to the Queen and the mayor of Greater Manchester Andy Burnham to express condolences.

"Manchester has been home to the Irish and so many nationalities for centuries and at this terrible time I want to send the people of this great and welcoming city not only our sympathy but our solidarity," he said.

Members of the Catalan Government also observed a minute's silence in Barcelona to remember the victims of the attack.

Cannes Film Festival announced a minute's silence to honour the victims of the attack.

The world-famous movie event has been taking place in the south of France amidst tight security in the wake of a series of attacks in the country.

In a statement, the Festival said: "The Festival de Cannes would like to express its horror, anger and immense sadness following the attack on the public and the city of Manchester last night.

"This is yet another attack on culture, youth and joyfulness, on our freedom, generosity and tolerance, all things that the Festival and those who make it possible, the artists, professionals and spectators, hold dear."

It added: "The Festival de Cannes invites all festival-goers to show their solidarity with the victims, their families and the British people by observing a minute's silence this Tuesday 23 May at 3pm."

The Hollywood Reporter said a champagne reception due to be held on Tuesday in Cannes to celebrate Pixar's Cars 3 was cancelled.