Former Cuban president Fidel Castro says American society is marked by ''profound racism'' and it's a ''pure miracle'' that US presidential nominee Barack Obama has not been assassinated.

''Profound racism exists in the United States,'' Dr Castro wrote in a commentary that appeared on the website www.cubadebate.cu at the weekend as he weighed in on the United States presidential race ahead of the November 4 election.

''Millions of whites cannot reconcile in their minds with the idea that a black man with his wife and children would move into the White House, which is called just like that, 'White'.''

He said it was a ''pure miracle'' the Illinois senator, who became the first black politician to win the Democratic Party's presidential nomination, had not been assassinated thus far.

The ailing Cuban communist leader described Senator Obama as a politician who ''has the habit of looking at his opponent with serenity and laughing at his rhetorical attacks''. Dr Castro also mocked Republican nominee John McCain's poor grades at the naval academy and said vice-presidential nominee Sarah Palin ''knew nothing at all about anything''. AFP