As Spanish police on Friday hunted for the driver who rammed a van into pedestrians on an avenue crowded with tourists in Barcelona, world leaders have condemned the attack, expressing outrage and solidarity with the victims.

- Spain -

The Spanish royal family issued an unusually strongly-worded statement: "They are assassins, criminals who won't terrorise us. All of Spain is Barcelona."

FC Barcelona said it was "deeply saddened" by the tragedy and the team's talismanic striker Lionel Messi said separately that people must reject "any act of violence".

"There are many more of us who want to live in a world in peace, without hate and where respect and tolerance are the basis of coexistence," he added.

- United States -

President Donald Trump tweeted: "The United States condemns the terror attack in Barcelona, Spain, and will do whatever is necessary to help. Be tough & strong, we love you!"

Secretary of State Rex Tillerson added: "Terrorists around the world should know -- the United States and our allies are resolved to find you and bring you to justice."

- Germany -

In a statement, the office of German Chancellor Angela Merkel said they were thinking of the victims of the "revolting attack" with "profound sadness".

- Russia -

President Vladimir Putin called for the world to unite in an "uncompromising battle against the forces of terror".

"We decisively condemn this cruel and cynical crime against civilians," Putin wrote in a telegram of condolences to Spanish King Felipe VI

- United Nations -

A spokesman said UN Secretary General Antonio Guterres "condemns today's terrorist attack on Barcelona" and "hopes that those responsible for this heinous violence will be swiftly brought to justice."

- European Union -

European Commission President Jean-Claude Juncker said: "I send my deepest condolences to the families and loved ones of the victims, as well as to Prime Minister Rajoy and the people of Spain. My thoughts are with the people of Barcelona."

Flags were flying at half mast in front of the EU Commission headquarters in Brussels on Friday, where a minute's silence was also to be held at midday to remember the victims of the attack. 

- France -

President Emmanuel Macron voiced "France's solidarity" with Spanish citizens following what he called "a tragic attack".

Paris Mayor Anne Hidalgo said: "Parisians are at your side. Barcelona and Paris are cities that share love and tolerance. Our values are much stronger than this heinous and cowardly act of terrorism".

In Paris, a mass is to be held in Notre Dame cathedral on Sunday evening dedicated to the victims, the archdiocese of the French capital announced.

"I would like to assure you of my prayers for the victims and the Catholic community of Barcelona and the Catalans and all of Spain," wrote archbishop, Cardinal Andre Vingt-Trois in a message to his counterpart in Barcelona, Cardinal Juan Jose Omella.

- Britain -

British Prime Minister Theresa May tweeted: "My thoughts are with the victims of today's terrible attack in Barcelona ... and the emergency services responding to this ongoing incident. The UK stands with Spain against terror."

London Mayor Sadiq Khan called the attack "barbaric", adding: "London stands with Barcelona against the evil of terrorism."

- The Netherlands -

It was a "cowardly attack against innocent people," Prime Minister Mark Rutte said in a statement on his Facebook page, calling it a "black day at a place where many people around the world gathered."

- Turkey -

Foreign Minister Mevlut Cavusoglu said Turkey strongly condemned the "heinous terrorist attack". 

- The Vatican -

Pope Francis's spokesman said in a statement: "The Pope prays for the victims of this attack and wishes to express his closeness to all the Spanish people, especially the wounded and families of the victims."

- Portugal -

Footballer Cristiano Ronaldo, a star with Spanish premier club Real Madrid, said he was "dismayed" by the attack and voiced "support and solidarity with the families and friends of the victims".    

- China -

Chinese President Xi Jinping and Premier Li Keqiang sent a letter of condolences to the King of Spain and the Spanish prime minister.

"China firmly opposes all forms of terrorism, supports efforts to combat terrorism and supports peace and stability, and would like to cooperate with Spain to enhance counter-terrorism operations," the president said.

- Philippines -

"The Philippines condemns in the strongest terms this disturbing act of terror perpetrated by extremists against innocent men, women and children in Barcelona," Foreign Affairs Secretary Alan Peter S. Cayetano said in a statement.

"We stand in solidarity with the people of Catalonia and all of Spain and the rest of the world as we fight this common scourge," Cayetano said. 

- Hungary -

Hungarian Prime Minister Viktor Orban said: "This terrible attack reinforces our conviction that the most important task in the coming period will be the restoration of security for Europe and European people."

- Austria -

Austrian President Alexander van der Bellen said: "Europe and the whole world are united against terrorism." 

- Australia - 

Australian Prime Minister Malcolm Turnbull said: "The Australian people condemn the terrorist attack, the Islamist terrorist attack in Barcelona overnight." 

"Our love, our prayers are with the victims and their families... we stand in absolute, resolute solidarity with the people of Spain in the fight against Islamist terrorism," he told reporters.

- New Zealand -

New Zealand Prime Minister Bill English tweeted: "My thoughts are with the families of those killed following the horrendous attack in Barcelona."