French custom officials have seized a record 51 kilograms of methamphetamine hidden in a shipment of breakfast cereal.

The haul is estimated to have a street value of over £3 million, the customs department said in a statement, and is the biggest single seizure of the drug on French territory.

Customs officers at Charles de Gaulle airport in Paris were checking cartons containing bags of cereal when they found them to be "unusually heavy".

They opened the bags and found crystals of the drug wrapped in aluminium foil in 40 of the 70 bags, which were being transported from Cameroon to Malaysia.

Methamphetamine is a strong and highly addictive stimulant, popular for recreational use and to help workers stay alert and energetic during long and night shifts.

Users of the drug experience an intense rush, heightened attention and curbed appetite. Over time addicts often suffer anxiety, weight loss and tooth decay.

The drug has been popular in poorer Asian countries for many years, but is now thought to be gaining popularity in richer nations such as South Korea, Japan, Singapore and Malaysia.

The substance is sold in various forms in Asia including as a component of a local drug called yaba, which is extremely prevalent in southeast Asia. The drug is the most popular illegal substance in the region and can cost less than a fast food meal at Burger King.

Meanwhile, a Reuters investigation in July found west Africa was playing a "new and fast-growing role" in the global drug trade, "not just as a transit point for drugs but also as a producer of amphetamine-type stimulants".

Local and international officials told Reuters west African criminal groups are now producing and exporting hundreds of millions of dollars worth of methamphetamine every year, most of which is shipped to Asia.

The synthetic drug is derived from ephedrine or pseudoephedrine, two common medicines used to treat conditions like nasal decongestion and asthma. It can be manufactured with basic equipment and is extremely profitable. One kilo of meth costs just over £1000 to make in West Africa but sells for more than £100,000 in Japan.

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According to officials spoken to by Reuters, west Africa is an easy place to produce the drug because of weak controls on the import of ingredients.

Production has increased from virtually zero five years ago, Pierre Lapaque head of UNODC in West and Central Africa said, to around 1.5 tonnes per year.