WASHINGTON: President Barack Obama used an event honouring Holocaust heroes Wednesday to warn of rising anti-Semitism and to stress America's "unbreakable" bonds with Israel.

"We must confront the reality that, around the world, anti-Semitism is on the rise. We cannot deny it," Obama said, declaring "we are all Jews", on what was International Holocaust Remembrance Day.

"An attack on any faith is an attack on all of our faiths," he said as he cited instances of discrimination in Europe, Asia and the United States (US).

Obama said that the United States (US) was at the forefront of efforts to combat anti-Semitism and would remain a friend to Israel.

Obama has been at pains to stress close ties with Israel amid a series of rows with the country's government and particularly Prime Minister Benjamin Netanyahu.

The pair have sparred publicly over settlement building and the Iran nuclear deal, which Netanyahu fiercely opposed.

"America's commitment to Israel's security remains, now and forever, unshakeable," he said in a speech at the Israeli embassy.

"It would be a fundamental moral failing if America broke that bond."