THE use of nuclear weapons will grow increasingly likely by 2025, US intelligence warned in a report on global trends that forecasts a tense, unstable world shadowed by war.

"The world of the near future will be subject to an increased likelihood of conflict over scarce resources, including food and water, and will be haunted by the persistence of rogue states and terrorist groups with greater access to nuclear weapons," said the report.

"In one sense, a bad sense, the pace of change that we are looking at in 2025 occurred more rapidly than we had anticipated," said Thomas Fingar, deputy director of National Intelligence. One overarching conclusion of the report is that "the unipolar world is over, (or) certainly will be by 2025," Mr Fingar said.

"The potential for conflict will be different then and in some ways greater than it has been for a very long time," Mr Fingar said.

The report has good news for some countries:

- A technology to replace oil may be underway or in place by 2025;

- Multiple financial centres will serve as ``shock absorbers'' of the world financial system;

- India, China and Brazil will rise, the Korean peninsula will be unified in some form, and new powers are likely to emerge from the Muslim non-Arab world.

"Over the next 15-20 years, reactions to the decisions Iran makes about its nuclear program could cause a number of regional states to intensify these efforts and consider actively pursuing nuclear weapons," the report said. "This will add a new and more dangerous dimension to what is likely to be increasing competition for influence within the region," it said.