Canada’s province of British Columbia is starting a first-in-the-nation trial decriminalising small amounts of hard drugs such as cocaine and heroin.

From Tuesday, adults can possess up to 2.5g of such drugs, as well as methamphetamine, fentanyl and morphine.

Canada’s federal government granted the request by the west coast province to try out the three-year experiment.

It follows a similar policy in the nearby US state of Oregon, which decriminalised hard drugs in 2020.

Ahead of the pilot’s launch, British Columbia and federal officials outlined the rules under the federally approved exemption from the Controlled Drugs and Substances Act.

While those substances will remain illegal, adults found in possession of a combined total of less than 2.5g of the drugs will not be arrested, charged or have their substances seized. Instead, they will be offered information on available health and social services.

Federal minister of mental health and addictions Carolyn Bennett on Monday called the move “a monumental shift in drug policy that favours fostering trusting and supportive relationships in health and social services over further criminalisation”.

Some 10,000 residents have died from drug overdoses since British Columbia declared drugs to be a public health emergency in 2016, officials said.

“Decriminalising people who use drugs breaks down the fear and shame associated with substance use and ensures they feel safer reaching out for life-saving supports,” said Jennifer Whiteside, the British Columbia minister for mental health and addictions.

Thousands of police officers in the province have been offered training on the rule change, including those in Vancouver, the largest city in the province.

The programme will run from 31 January 2023 until 31 January 2026, unless it is revoked by the federal government.

Some experts have questioned the 2.5g limit, saying that it is not enough to account for the habits of many addicts.

There are some exemptions to the scheme.

The sale of drugs remains illegal. It is also illegal to possess drugs on the grounds of schools, childcare facilities and airports.

Canada legalised the use of recreational cannabis for adults nationwide in 2018.

But the four drugs now allowed in small quantities remain prohibited, meaning there are no plans to sell them in stores, unlike marijuana. Trafficking them across borders also remains illegal.