NEW YORK (REUTERS) - The chances have increased over the past month that the much-feared El Nino phenomenon, which has the potential to wreak havoc on global crops, would strike by summer in the Northern Hemisphere, the federal US

weather forecaster said on Thursday.

In its monthly report, the Climate Prediction Center, an agency of the National Weather Service, pegged the likelihood at more than 50 per cent.

In March, it said there was about a 50 per cent chance of the weather pattern that causes floods and droughts across the world during the summer or autumn.

On Tuesday, Australia's Bureau of Meteorology pegged the chances of El Nino in 2014 at more than 70 per cent.

El Nino - a warming of sea-surface temperatures in the Pacific - affects wind patterns and can trigger both floods and drought in different parts of the globe, curbing food supply.