US President Donald Trump has declared himself the best friend Israel has ever had.

He also declared that Jewish-Americans had been wrong to vote for Democrats under his predecessor Barack Obama, reports AFP.

"So many of you voted for people in the last administration," he said.

"Someday you'll have to explain that to me because I don't think they liked Israel too much."

By contrast, Trump said, "the Jewish state has never had a better friend in the White House than your president, Donald J. Trump."

He was speaking at a meeting of the Israeli-American Council, a non-profit whose funders include billionaire Jewish-American casino magnate Sheldon Adelson and his wife Miriam -- both of them high-profile Trump supporters.