By Peter Apps, Political Risk Correspondent
LONDON (Reuters) - Social unrest is making the world less peaceful for the third year running and economic strains could point to rising risks in China, a think tank said on Wednesday.
The Global Peace Index -- which tracks 23 indicators from military spending to crime levels to conflict and disputes with neighbors -- showed economic factors are at the heart of unrest including the "Arab Spring."
Rising food prices have helped trigger revolts in Egypt, Tunisia and elsewhere, with some leading to serious bloodshed, while austerity measures in Europe have also helped bring protesters on the streets.
There were some positive trends too. Despite conflict in Ivory Coast and Libya and cross-border tensions between North and South Korea, interstate wars are generally becoming less common and relations among countries are improving.
"The dramatic changes we are seeing this year are caused not by war between countries but struggles between people and their governments," said Steve Killelea, founder and chairman of the Institute of Economics and Peace which produced the report.
"What's driving it is partly linked to the financial crisis and it has also been linked to the rise in food prices."
Going forward, Killelea -- an Australian former businessman who started the index five years ago -- said the key country to watch was China, which could experience violent unrest if the economy slowed in the years ahead.
"China cannot keep growing forever and when a slowdown happens it could face serious problems," he said.
But only three years after its financial meltdown destroyed its banks and prompted some of its first ever riots, Iceland returned to its position at the top of the list as world's most peaceful country.
Japan and New Zealand also performed well despite natural disasters whilst Ireland saw the smallest rise in unrest of any troubled Euro zone state, Killelea said, almost certainly because of the way their societies are organized.
Well functioning governments, relatively homogenous societies and equitable distribution of wealth, good secondary education and press freedom were amongst the most important factors in ensuring peace, he said.
"Countries with these structures are much more able to adapt, to pull together in difficult times," he told Reuters. "And China is lacking many of them."
(Editing by Maria Golovnina)