Image copyright AP Image caption An average of 15 drug overdoses a month occur in the Canadian city of Vancouver

Nine people have died in Vancouver in the past 24 hours from an overdose of the painkiller fentanyl opioid, officials say.

Mayor Gregor Robertson said these were "desperate times" for the Canadian city, adding that more deaths were expected.

"It's hard to see any silver lining right now when we haven't hit rock bottom," Mr Robertson said.

Drug abuse in Canada claimed the lives of 2,000 people in 2015.

The government has invested tens of millions of dollars in public health emergency responses in recent years, but Mr Robertson said that more was needed.

Police Chief Adam Palmer also called for more help for the city's addicts. "Can you imagine nine people dying from another cause in one day in our city?" he said.

Vancouver has seen an average of 15 drug overdoses a month, with dozens more deaths still under investigation, Mr Palmer said.

The city's coroner said that morgues had reached capacity.

Most of the deaths occurred in the Downtown Eastside neighbourhood, where drugs can be easily bought, Mr Palmer said.

Two milligrams of pure fentanyl, the size of about four grains of salt, is enough to kill an average adult.

In April, the US singer Prince died of an accidental overdose of the dangerously powerful synthetic drug.

What is fentanyl?

Fentanyl is an extremely strong painkiller, prescribed for severe chronic pain, or breakthrough pain which doesn't respond to regular painkillers.

It is an opioid painkiller which means it works by mimicking the body's natural painkillers, called endorphins, which block pain messages to the brain.

It can cause dangerous side effects, including severe breathing problems.

The risk of harm is higher if the wrong dose or strength is used.