"The canners and freezers of vegetables fear that stock levels may not make up for the shortfall of this year's crop," Susanne Meyer, OEITFL Secretary General, told Reuters.

"Of course, we cannot speak for farmers directly or those delivering fresh produce, but if there has been an adverse impact on the raw materials for us, then of course it will be the same for shops and supermarkets."

Meyer said the current heatwave, which has seen most of Europe enduring temperatures of over 30 degrees Celsius (86 F), has plunged the industry into its worst situation in 20 years.

"The position is reminiscent of the catastrophic year 1976 when a comparable lack of rain was registered which now leaves them with less production than anticipated under normal weather conditions," she said.

"A further aggravating factor was the long, cold, and wet spring which inhibited the sowing and germination of seeds, itself leading to a much shorter season."

Europe's farmers are facing heavy financial losses due the current weather conditions with harvest forecasts continuing to be cut on a daily basis.

On Wednesday, eight countries sought permission for their farmers to use land that is normally prohibited under EU rules, as they run out of land on which to feed their animals.

The unusually high temperatures and lack of water leaves the processed vegetables market facing massive shortages of main produce such as peas, cauliflower, spinach, beans, broad beans, baby carrots, broccoli, and onions.

According to OEITFL there has been a substantial reduction in principal producer countries such as Belgium, France, Britain, the Netherlands, Denmark and Sweden, where pea crops are down some 20 percent.

The scenario is the same for spinach with anticipated shortages of up to 20 percent, and with cauliflower crops down by up to 30 percent.

Meyer said her organisation is particularly concerned about the situation in Eastern Europe.

"In Poland, for some vegetables like beans, the crop is even expected down by 40 percent, and in Hungary zucchini volumes are also down some 40 percent," Meyer said.

While the current weather had already taken its toll, the outlook for the autumn also is grim.