Countries with large populations and low levels of development are most likely to see a rise in the risk of armed conflict after extreme weather events, according to a new study that researchers said underscored the need to boost their resilience.

Almost 1 in 3 conflicts in large countries with ethnic tensions and low levels of development over the last 25 years broke out within seven days of such a disaster, said scientists from Germany, Sweden and Australia.

Even small-scale disasters can increase the risk of conflict in vulnerable places, according to the research paper, published in the journal Global Environmental Change this week.