Boxing legend Muhammad Ali, one of the best-known Muslims in the United States, appeared on Wednesday to join the chorus condemning the proposal by Republican presidential front-runner Donald Trump to temporarily stop Muslims from entering the country.

"We as Muslims have to stand up to those who use Islam to advance their own personal agenda," Ali, 72, said in a statement that appeared in a report by NBC News headlined "Presidential candidates proposing to ban Muslim immigration to the United States", but did not actually name Trump.

The Louisville, Kentucky-born Ali, a three-time world heavyweight champion who joined the Nation of Islam in 1964 and later converted to Sunni Islam, also took aim at Islamist extremists.