WASHINGTON, USA (AFP) — The start of Mitt Romney's foreign tour was overshadowed yesterday by a reported remark by an aide that President Barack Obama doesn't understand the "Anglo-Saxon heritage" shared by Britain and the US.

In the context of previous jibes that the Democratic incumbent, the US's first black leader, does not understand American values and business practice, the latest alleged comments were seen as racially charged.

British newspaper The Daily Telegraph said it had interviewed two Romney advisers who said their man would be better than President Barack Obama at reinforcing the special bond between the US and Britain.

"We are part of an Anglo-Saxon heritage, and he feels that the special relationship is special," an unnamed adviser told the Telegraph. "The White House didn't fully appreciate the shared history we have."

The British paper also quoted an adviser saying Obama "is a left-winger" who "doesn't value the NATO alliance as much. He's very comfortable with American decline and the traditional alliances don't mean as much to him".

The comments caused scandal just as Romney arrived in London to kick off a three-nation tour where his campaign has said he won't attack Obama's record, and the White House seized on the remarks as undignified and disturbing.

"Despite his promises that politics stops at the water's edge, Governor Romney's wheels hadn't even touched down in London before his advisers were reportedly playing politics with international diplomacy, attempting to create daylight between the United States and the United Kingdom where none exists," Vice-President Joe Biden said in a statement.

The comments, Biden said, "are a disturbing start to a trip designed to demonstrate Governor Romney's readiness to represent the United States on the world's stage."

Senior Obama re-election strategist David Axelrod called the comments "stunningly offensive."