The 'party in a pouch' Shotpaks are designed to pack a powerful punch with a double measure of 34 per cent proof vodka mixed with fruit flavourings.

But even before the official launch is complete, Wymbush-based distributers Chilling Rocks Beverages Ltd has incurred the wrath of one local MP and now has to answer probing questions from alcohol watchdogs, the Portman Group.

"We can't understand what the problem is," said Chilling Rocks spokesperson Virginia Foster. "We think we have an excellent product, which is being marketed in a tasteful and responsible manner."

Northampton MP Sally Keeble says the Shotpak rip-and-go concept promotes a "casual" attitude to drinking. She has also slammed allegedly over-sexy internet ads showing girls hiding ShotPaks in their boots and clothing to go into nightclubs.

"Firms are not supposed to link getting drunk with sex, and this product is being advertised on MySpace with pictures that verge on being soft porn," she said.

But the Wymbush company claims to have no knowledge of these ads, which come from America where Shotpaks are manufactured.

"Our promotional picture is the back view of a woman wearing a bikini top, slipping a Shotpak into the pocket of her shorts. What is wrong with that?" asked Virginia.

She said the lightweight and flexible pouches, though they do resemble children's soft drink packaging, are clearly marked with Government health warnings, including the message 'please drink responsibly'.

"We don't think they will encourage under-age drinking at all. We believe the price - £3 a pouch - will actually deter the teenage market and they will be more popular with older people. Already easyJet has shown an interest because they are ideal for airline travellers."

This week the Portman Group confirmed it would be investigating the products under its standard complaints procedures following the MP's complaints.

Meanwhile Chilling Rocks staff, confident of success in off-licences, supermarkets and convenience stores, are stocking up on more supplies from the USA manufacturing plant – ironically based in Temperance.