Saudi's Naimi calls current oil prices sustainable

*Saudi minister warns of political risk to oil spending

*Oil price at "sustainable" levels after econ crisis-Naimi

*Saudi to spend $107 bln in energy sector over 5 yrs

CHICAGO, April 28 (Reuters) - Saudi Oil Minister Ali al-Naimi warned on Wednesday that politically motivated policies in major oil consuming countries to reduce oil imports or push new forms of energy could put the world's energy security at risk.

The minister added that he thinks today's oil prices are at "more sustainable levels".

In a thinly veiled reference to U.S. efforts to wean itself from imported Middle East crude oil, Naimi hoped such rhetoric would not become policy, the minister was set to tell the U.S.-Saudi Business Opportunities Forum in Chicago, according to an advanced copy of his speech.

"It is my sincere hope that often-repeated political statements like reducing oil imports from this or that region are not translated into political actions," he said.

He also repeated his support for current prices, which, at nearly $83 a barrel, are slightly above the $70-$80 band that he has said is ideal for producers and consumers.

"The worst financial and economic crisis in decades is slowly fading and the world is entering a new growth trajectory," Naimi said.

"As the oil prices are back to their more sustainable levels, I am more optimistic about the future of energy and oil demand."

The comments come as oil was trading above the $80 a barrel range that Saudi officials, including Naimi, recently called "beautiful" for both producer and consumer countries.

Oil prices surged to a record $147 a barrel in mid-2008, slamming consumers, before receding to around $33 a barrel later that year, hurting producer countries.

But Naimi warned that political goals to reduce oil imports in major consumption regions like the United States and encourage alternative energy investments instead, may hurt investment in fossil fuels.

Naimi said that Saudi Arabia, the top world oil exporter, holds approximately 12.5 million barrels a day of oil production capacity and a goal of keeping at least 1.5 and 2 million barrels of spare capacity to supply world markets whenever oil demand rises.

Costs of keeping that spare capacity have been rising, Naimi said. To develop a barrel of spare capacity at the Kingdom's Khurais oil field costs approximately $10,000, Naimi estimated, or double the cost of developing capacity in Saudi Arabia's Empty Quarter a decade ago.

Meanwhile, costs of developing spare capacity at the offshore field of Manifa are about triple the levels of a decade ago, the oil minister said.

Saudi Arabia plans to spend $107 billion over the next five years in its upstream and downstream oil and gas sectors, Naimi said.

(Reporting by Karl Plume in Chicago. Writing by Joshua Schneyer in New York. Editing by Carole Vaporean)