Valencia grower grouping Ava-Asaja has said that the prices growers receive for their watermelons are "perverse and immoral". Levels have plummeted this week to just €0.02 a kg at the farm-gate compared to the €0.12 it costs to grow the fruit.

Association president Cristóbal Aguado said: "National and European administrations have abandoned their growers with legislation that is excessively permissive towards the abuses of the large multiples and the signing of international agreements that only help third countries and damage Spanish horticulture."

He cited the example of €0.15 at the farm-gate for a 5kg watermelon in the Valencia region compared to €30 for a fruit of the same weight on the market in Geneva. "This is incomprehensible when there is even less supply into the marketplace after the frosts which affected summer fruit," said Aguado.

He is calling on national government in Spain to legislate for fair pricing which will allow the market to be regulated at times of crisis at source as well as profitability insurance to safeguard the long-term livelihood of professional growers.

Watermelon was selling for 550p for 20kg on New Covent Garden Market this week and at £2.99 for 4.5kg in Sainsbury’s.