Tens of thousands packed a rally in Washington on Tuesday to support Israel and to condemn anti-Semitism in a riposte to weeks of largely pro-Palestinian demonstrations across a deeply divided United States.

With senior members of Congress addressing the event on the National Mall, near the Capitol, the crowd rapidly swelled with people wearing the white and blue colors of Israel.

Many were waving placards calling on Palestinian terrorist group Hamas to free hostages taken during their surprise 7 October attack on Israel, which authorities there say killed more than 1,200 people.

"Our hearts are bruised and seeping with misery. Why is the world accepting that 240 human beings from almost 30 countries have been stolen?" Rachel Goldberg, the mother of Hersh Goldberg-Polin, one of the 240 people believed taken hostage by Hamas, told the crowd.

Speaking by video link from Jerusalem, Israeli President Isaac Herzog told demonstrators in the March for Israel that they were "marching for the right of every Jew to live proudly and safely in Israel and the US and the world."

"No one will break us," he said.

US Senate Majority Leader Chuck Schumer — a Democrat — and House Speaker Mike Johnson — a Republican —also spoke, as well as family members of the hostages.

"America feels your pain," said Schumer, the highest-ranking Jewish elected official in the US.