"Our hearts are hostage in Gaza," read the metal tag he received from Malki Shem-Tov, the father of hostage Omer Shem-Tov, in a video of Musk's visit issued on Monday by the office of Israeli President Isaac Herzog.

Musk placed it around his neck. Later on Monday he wrote on X: "I will wear it every day until your loved ones are released."

The dog-tags, prevalent throughout Israel, mark the Oct. 7 cross-border killing spree by Hamas during which 240 people were dragged back to Gaza.

On Nov. 15, Musk posted on X his agreement with a post that falsely claimed Jewish people were stoking hatred against white people, saying the user who referenced the "Great Replacement" conspiracy theory was speaking "the actual truth".

Following the post, major U.S. companies including Walt Disney, Warner Bros Discovery and NBCUniversal parent Comcast suspended their advertisements on X, formerly known as Twitter.

The White House criticised Musk for what it called an "abhorrent promotion of antisemitic and racist hate" that "runs against our core values as Americans".

Musk has said he is against antisemitism and anything that "promotes hate and conflict" and stated that X would not promote hate speech.

(Writing by Howard Goller; Editing by Nick Macfie)