Colombian coca plant farmers have developed genetically modified strains of the plant, the Financial Times claims.
Anti-drug officers in the remote Sierra Nevada region of northern Colombia have discovered a new variety of coca plant that can grow up to 2.7m (9ft) tall - double the normal size - and produce four times as much cocaine as ordinary coca plants.
Foreign agronomists have helped the coca growers to develop the new strain of plant, which is resistant to many commonly used herbicides and can yield as much as four times the regular concentration of cocaine, the FT reports
However Camilo Uribe, a Colombian toxicologist, told Reuters that there is no evidence that the plants are genetically modified. Their extreme size could be because of "an excess of fertiliser", he said.
A spokesman for the US embassy in Bogota told BBC News that there was "no scientific proof" that "transgenic coca" had been developed, although rumours of its existence were rife.
The increased yield from these new strains of coca plant could help to explain why cocaine production has stayed constant despite the Colombian government's claim that the area under coca cultivation has halved since 2000.
Under the government of President Alvaro Uribe, elected in 2002, Colombia has attempted to crack down on cocaine production across the country.
Uribe is an enthusiastic supporter of Plan Colombia, a US initiative to train Colombia's security forces and provide them with equipment and intelligence to tackle drug traffickers and destroy coca crops before they can be processed into cocaine.
Colombia is the world's third largest recipient of US military aid. ®