PM says Alberta ‘essential’ to Canada as separatists push for independence

Alberta premier calls for referendum on secession after judge ruled initiative to force binding vote invalid

The Canadian prime minister, Mark Carney, has said that Alberta is essential" to the country's future, hours after the province's leader moved the oil-rich region closer toward a referendum on independence.

Separatists in the western province spent months collecting signatures seeking to trigger a binding October vote on seceding from the nation.