TOKYO (REUTERS) - Japan's weather bureau said on Wednesday that an El Nino weather pattern, which can trigger drought in some parts of the world while causing flooding in others, had emerged during the summer for the first time in five years and was likely to continue into winter.

That marks the first declaration by a major meteorological bureau of the much-feared El Nino phenomenon, which had been widely expected to emerge this year.

El Nino - a warming of sea-surface temperatures in the Pacific - can prompt drought in Southeast Asia and Australia and heavy rains in South America, hitting production of food such as rice, wheat and sugar.

The Japan Meteorological Agency (JMA) forecast last month that the possibility of an El Nino pattern forming this winter was higher than the 50 per cent it had projected in its previous monthly prediction.

But on Wednesday it said that an El Nino had emerged between June and August, continuing into November.

"We can't tell whether or not El Nino will continue until spring, but we can say that there is a higher chance of it continuing in the winter," said Ikuo Yoshikawa, a JMA forecaster.

The Japanese weather bureau does not classify or predict the size of El Nino, he said.

Last week, the Australian Bureau of Meteorology said that climate models suggest El Nino weather conditions would occur over the next three months, although related weather patterns are already being witnessed.

The US weather forecaster also projected last week a 65 per cent chance of El Nino conditions during the Northern Hemisphere winter and into spring, up from a 58 per cent chance predicted early in November.