* To publish 2025 forecast in April report, 2 to 3 months earlier

* OPEC last week gave surprise early 2025 forecast

* IEA, OPEC disagree on 2024 oil demand strength, peak oil view

(Adds detail in paragraph 11)

LONDON, Jan 24 (Reuters) - The International Energy Agency plans to bring forward publication of its first 2025 oil demand forecast in its monthly report by two or three months to April, the agency told Reuters, after OPEC expedited its forecast by six months.

The Organization of the Petroleum Exporting Countries and the IEA are the two most closely watched oil forecasters, whose monthly reports can move oil prices and provide insight into the assumptions behind OPEC supply policy.

"We plan to publish the 2025 forecast in April as opposed to June/July previously," Toril Bosoni, head of the IEA's Oil Industry and Markets Division, told Reuters in response to an emailed question.

"The reason for this is that we will publish the Medium Term outlook in June so to avoid the overlap – and get a first detailed view on 2025 before looking out to 2030 - we advanced the date."

The IEA and OPEC disagree on the strength of demand growth in 2024, reflecting their divergent forecasts on how quickly the world will shift from fossil fuels.

OPEC believes oil use will keep rising over the next two decades, while the IEA, which represents industrialised countries, predicts it will peak by 2030.

Their differing views have led the bodies to clash over investment in new oil supply. The IEA says the end of the growth era for fossil fuels undercuts the rationale for investment.

In a break with its tradition of publishing its first forecast for the next year in July, OPEC last week predicted demand will rise by 1.8 million bpd in 2025 and said it brought publication forward to give "long-term guidance for the market".

On the same day, OPEC Secretary General Haitham Al Ghais published an article disputing that demand was near a peak, and reiterated the group's call for continued oil industry investment.

So far this year, the oil market has been buffeted by uncertainty as doubts about the global economy and demand strength have offset the more bullish impact of possible supply disruption.

OPEC forecasts world oil demand will expand by 2.25 million barrels per day (bpd) in 2024, a mild slowdown from 2.46 million bpd in 2023, with total oil use averaging 104.4 million bpd in 2024, bolstered by air travel and road fuel demand.

The IEA expects oil demand growth in 2024 to halve to 1.24 million bpd, from its figure for growth of 2.3 million bpd in 2023, partly because an increasing global electric vehicle fleet is curbing gasoline demand.

The difference between the OPEC and IEA demand forecasts for this year is about 1% of world demand, almost equivalent to OPEC member Libya's production.

A source with knowledge of the matter did not provide details of what the IEA would forecast for 2025 demand, but said it was expected to show further deceleration towards the 2030 peak demand timeline. (Reporting by Alex Lawler, Ron Bousso and Natalie Grover; editing by Jane Merriman and Barbara Lewis)