YOKOHAMA, Japan - Psychological powers - not refereeing conspiracies - have fuelled South Korea's historic run to the World Cup semi-finals, according to a leading football doctor and referees.

As the co-hosts prepared to take on Germany in Tuesday's first semi-final in Seoul, referees and FIFA President Sepp Blatter denied allegations of a conspiracy involving South Korea after controversial decisions in their recent matches.

Football's medical expert Toni Graf-Baumann said the Koreans had shown remarkable "mental fitness" in controversial defeats of three strong European sides - Portugal, Italy and Spain.

"We cannot ignore the fact that some other sports have suffered the ignominy of corruption in recent years," said Senes Erzik, the chairman of the Referees' Committee of soccer's world governing body FIFA.

"But football is a sport that does not lend itself to such dishonesty. Anybody who really knows the game, the people involved in it, and the control mechanisms that are in place, knows in their hearts that this is true."

Criticism of the refereeing at the World Cup gathered pace after Spain's quarter-final defeat to South Korea last week.

Spain lost on penalties after having two goals disallowed, one of them an extra-time "golden goal".

Italy had a goal disallowed for offside and playmaker Francesco Totti was controversially sent off before they lost 2-1 in extra time in the second round to the Koreans.

In a brief statement FIFA President Sepp Blatter said: "Any allegations of a conspiracy in favour of Korea Republic are dismissed in their entirety."

Germans of Asia

Before the World Cup, Korea had not won a single game in their five previous appearances at the finals.

But this team has become known as the "Germans of Asia" because of the way their superior fitness helps them fight until the final seconds - the common denominator of successful teams from Germany, who have won the World Cup three times.

"Korea Team Fighting" has been one of the slogans for the side at the finals.

"They are very mentally fit," said FIFA's German medical expert Graf-Baumann. "They play such effective football. They are so fresh. Also they don't over-react to refereeing decisions. They accept them and get on with their effective game."

Erzik said some of the media had been trying to explain away upsets at the World Cup with "spurious allegations of one type of conspiracy or another".

"As the chairman of the FIFA Referees' Committee, I state here unequivocally that all such allegations, accusations and insinuations are totally without foundation," he said.

"I also wish to express my unwavering support for the referees and the assistant referees (linesmen) of this World Cup - including those who have already returned home - and my total belief in their integrity."

He added: "The unexpected is an integral part of the appeal of a sport in which the small team always stands a chance to beat the big one." (Agencies via Xinhua)