An El Nino weather pattern that could bring drought conditions to Australia's farmlands is 'very likely' this year and could be officially declared within weeks, the Australian Bureau of Meteorology (BOM) said on Wednesday.

El Nino, meaning 'little boy' in Spanish, is driven by an abnormal warming of the eastern Pacific Ocean, and creates havoc in weather patterns across the Asia-Pacific region.

'It's very likely we will have an El Nino this year,' David Jones, head of BOM climate analysis, told Reuters.

'At this stage we are not in a position to say we have an El Nino but in the coming weeks, if the current trends continue, we will have an El Nino event very shortly,' Jones said.

The bureau said in its latest El Nino report released on Wednesday that there was 'very little chance of the development stalling or reversing'.

'A more complete picture of the situation in the Pacific will be available next week when the final June indices are calculated,' said the report. The next report is due on July 8.

Australia is the world's fourth-largest wheat exporter and its grain production is still recovering from the worst drought in more than 100 years that reduced the 2006/07 crop to just 10.6 million tonnes and the 2007/08 crop to 13.0 million tonnes.

Its crop is currently experiencing a second strong year and is expected to be between 21 and 23 million tonnes this year.

Scientists have linked El Nino with Australian droughts. Warmer, moist weather moves towards the east, leaving drier weather in the western Pacific and Australia.

The bureau's latest report found that the eastern Pacific Ocean was continuing to warm, with sea temperatures one degree Celsius above normal, and trade winds were continuing to weaken.

The Southern Oscillation Index (SOI), calculated from monthly and seasonal fluctuations in air pressure between Tahiti and Darwin, remained at around negative 2, while the monthly value for May was negative 5.

A sustained negative SOI often indicates El Nino.

In its last two reports, the bureau said the odds of an El Nino forming were above 50 percent, which was more than double the normal risk of the event.

'The shift towards El Nino is certainly continuing and its got some significant momentum,' said Jones.- Reuters