Indian farmers have come up with what they think is the real thing to keep crops free of bugs.

Instead of paying hefty fees to international chemical companies for patented pesticides, they are reportedly spraying their cotton and chilli fields with Coca-Cola.

In the past month there have been reports of hundreds of farmers turning to Coke in Andhra Pradesh and Chattisgarh states.

But as word gets out that soft drinks may be bad for bugs and a lot cheaper than anything that Messrs Monsanto, Shell and Dow can offer, thousands of others are expected to switch.

Gotu Laxmaiah, a farmer from Ramakrishnapuram in Andra Pradesh, said he was delighted with his new cola spray, which he applied this year to several hectares of cotton. "I observed that the pests began to die after the soft drink was sprayed on my cotton," he told the Deccan Herald newspaper.

Coca-Cola has had a bad year in India.

Other farmers in Andra Pradesh state accused the company of over-extracting underground water for its bottling plants and a government committee upheld findings that drinks made in India by itself and PepsiCo contained unacceptable amounts of pesticide residue.

But Mr Laxmaiah and others say their cola sprays are invaluable because they are safe to handle, do not need to be diluted and, mainly, are cheap.

One litre of highly concentrated Avant, Tracer and Nuvocron, three popular Indian pesticides, costs around 10,000 rupees (£120), but one-and-a-half litres of locally made Coca-Cola is 30 rupees. To spray an acre would be a mere 270 rupees.

It is clearly not Coke's legendary "secret" ingredient that is upsetting the bugs. The farmers also swear by Pepsi, Thums Up, and other local soft drinks.

The main ingredients of all colas are water and sugar but some manufacturers add citric and phosphoric acids to give that extra bite to human taste buds.

Yesterday a leading Indian agriculture analyst, Devinder Sharma, said: "I think Coke has found its right use. Farmers have traditionally used sugary solutions to attract red ants to feed on insect larvae.

"I think the colas are also performing the same role."

The properties of Coke have been discussed for years. It has been reported that it is a fine lavatory cleaner, a good windscreen wipe and an efficient rust spot remover.

Uncorroborated reports from China claimed that the ill-fated New Coke was widely used in China as a spermicide.

Yesterday a spokesman for Coca-Cola in Atlanta said: "We are aware of one isolated case where a farmer may have used a soft drink as part of his crop management routine.

"Soft drinks do not act in a similar way to pesticides when applied to the ground or crops. There is no scientific basis for this and the use of soft drinks for this purpose would be totally ineffective".