9/11 anniversary: Biden calls for unity as US prepares to mark attacks

US President Joe Biden has urged unity as his country prepares to remember the victims of the 11 September attacks.

He paid tribute to the 2,977 people who lost their lives.

"We honour all those who risked and gave their lives in the minutes, hours, months and years afterwards," Mr Biden added, speaking of the emergency workers who responded to the attacks.

"No matter how much time has passed, these commemorations bring everything painfully back as if you just got the news a few seconds ago," the president said.

He acknowledged the "darker forces of human nature - fear and anger, resentment and violence against Muslim Americans" which followed the attacks, but said that unity had remained the US' "greatest strength".