Canada is still trying to reach 18,000 people stranded after floods and mudslides destroyed roads, houses and bridges in what could be the costliest natural disaster in the country’s history.

Receding floodwaters were helping rescue efforts on Thursday (local time).

But the downpour has blocked off entire towns in the province of British Columbia and cut access to the country’s largest port in Vancouver, disrupting already strained global supply chains.

Premier John Horgan declared a state of emergency and said the death toll would rise from the one confirmed fatality.

Many towns are in mountainous areas to the east and north-east of Vancouver with limited access.

Shoppers emptied grocery shelves, although the shortages were as much down to panic-buying as disrupted supply chains.

In Ottawa, federal Minister for Emergencies Preparedness Bill Blair said all river flows in the province were beginning to drop as the rain lightened.

“The situation remains critical, however. But there is in fact an improvement,” he told a briefing.

Ottawa has promised to send hundreds of air force personnel to British Columbia, the first of whom have already arrived. Thousands more are on standby.

Defence Minister Anita Anand said the military would be there for at least 30 days.

The flooding also hit the US state of Washington, as President Joe Biden noted before a meeting with Canadian Prime Minister Justin Trudeau.

“We’ve been good friends for a while … we’re both keeping our minds close to the families affected by the storms, flooding in the British Columbia area and the Pacific North-west,” he said in the Oval Office.

-AAP