* Sees global oil output coming close to peak by 2035
* Says oil price to exceed $100 in 2015, $200 in 2035
* Cuts 2035 oil use growth forecast by 6 mbpd to 99 mbpd
(Refiles to insert dropped word "conventional" in second paragraph)
By Muriel Boselli and Zaida Espana
PARIS/LONDON, Nov 9 (Reuters) - Global oil supplies will come close to a peak by 2035 when oil prices will exceed $200 a barrel, the International Energy Agency said on Tuesday, as China and other emerging economies drive demand higher.
The IEA, in its 2010 World Energy Outlook, said conventional crude oil output had already peaked and would flatten out in the next 10 years, boosting reliance on costlier and more polluting unconventional sources such as oil sands.
"Production in total does not peak before 2035, though it comes close to doing so," the IEA said in the executive summary of the report. That projection was according to the report's central case, the New Policies scenario.
The Paris-based IEA, which advises 28 industrialised countries, also raised its mid- and long-term oil price forecasts, despite slashing oil demand estimates by 2035, citing growing supply uncertainty.
Oil prices would rise even further if governments did not act to curb consumption, the IEA's chief economist and lead author of the report, Fatih Birol, told Reuters in an interview.
"The message is clear, the price will go up, especially if consuming countries do not make changes in the way they consume oil, especially in the transport sector," Birol said.
Oil hit $87.63 a barrel on Tuesday, the highest since October 2008, after hovering around $70-80 most of the year.
The world needed higher oil prices to change consuming habits substantially and spur investment as markets were becoming less sensitive to price changes, Birol said.
"All the net growth comes from non-OECD countries, almost half from China alone, mainly driven by rising use of transport fuels," the IEA said in the report.
While the IEA saw higher prices, it also cut its world oil demand estimate for the next 25 years by 6 million barrels per day (bpd) to 99 million bpd.
That remained an increase of 15 million bpd, equal to one and a half times the output of top global producer Russia.
Unconventional oil -- including supplies from oil sands in Canada and Venezuelan heavy oil, and liquid fuels obtained from natural gas and coal -- is expected to play a bigger role as growth in crude oil tails off.
"Crude oil output reaches an undulating plateau of around 68-69 million barrels a day by 2020, but never regains its all time peak of 70 million barrels per day reached in 2006," the IEA said.
Last year's edition of the report said global oil production was not forecast to peak before 2030 and conventional oil production was "projected to approach a plateau towards the end of the projection period."
While unconventional sources are abundant, they are more expensive to bring on stream and in general, their production gives off more greenhouse gases than that of conventional crude.
"They require large upfront capital investment, which is typically paid back over long periods," the IEA said.
"Mitigation measures will be needed to reduce emissions from unconventional oil production, including more efficient extraction technologies." (Writing by Alex Lawler; editing by William Hardy and Janet Lawrence)