Chinese President Xi Jinping called his US counterpart Barack Obama on Monday to express “deep condolences” over the 50 people killed by a gunman in a Florida gay nightclub, officials said.

Xi “expressed deep sympathy and sincere condolences to the American people” and “deep condolences” to the victims of the attack, the foreign ministry said on its website.

He joined an international outpouring of sympathy over the worst mass shooting in US history, after condemnation by Obama, Pope Francis and Britain’s Queen Elizabeth II.

Reacting to the latest in a long series of mass gun killings in the US, Obama said the FBI was “appropriately investigating this as an act of terrorism”.

“Although it’s still early in the investigation, we know enough to say that this was an act of terror and an act of hate,” he said, later ordering flags to be flown at half-mast.

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