The Australian government has raised the country’s terrorism threat level from “possible” to “probable”, reversing a change made nearly two years ago.

The prime minister, Anthony Albanese, made the announcement in Canberra on Monday.

Intelligence sources said the decision to raise the threat level was not triggered by any single issue or ideology, but noted an overall increase in polarisation in Australia and other western countries.

The sources said social cohesion was under strain and Covid-era grievances were being exacerbated by the Israel-Hamas conflict.