Image copyright AFP Image caption Some medical marijuana products are already legal in parts of the US

Tobacco firm Imperial Brands is investing in UK biotech company Oxford Cannabinoid Technologies (OCT).

The move comes as campaigning to allow marijuana products for medicinal purposes gathers pace.

A company subsidiary, Imperial Brands Ventures, is taking a stake in the UK firm, but its size is unknown.

Tobacco companies are trying to diversify away from their core product. Imperial's website bears the motto: "From tobacco to something better."

Imperial now sees itself as "a dynamic fast-moving consumer goods company borne out of a strong tobacco heritage".

OCT is a firm licensed by the UK Home Office that researches, develops and licenses cannabinoid-based compounds and therapies.

Imperial Brands' chief development officer, Matthew Phillips, said: "Our investment enables Imperial to support OCT's important research while building a deeper understanding of the medical cannabis market."

Imperial no longer makes cigarettes in the UK. Its last UK manufacturing site, the Horizon factory in Nottingham, closed down two years ago.