Oslo  - Norwegian Agriculture Minister Terje Riis-Johansen on Thursday called for a national campaign against the much-vilified Spanish slug.

Gardeners and farmers in Norway and neighbouring Sweden and Denmark have in recent years reported how the slug, also known as Arion lusitanicus, has become a major pest, destroying plants and flowers and other crops.

"The Spanish slug has become a major problem for many gardeners and I fear it will be a major nuisance for the agriculture sector," Riis-Johansen said when he addressed a conference on the topic in the west coast city of Bergen.

The minister offered 10,000 kroner (2,000 dollars) as a reward for the best method to destroy the troublesome slug.

In his remarks, he noted that current research suggested that the "cheapest and most efficient method was to collect the slugs" when they were sighted in gardens or fields.

"It helps, let us launch a counterattack," he said.

The Norwegian Agriculture Ministry has earmarked 3 million kroner (600,000 dollars) for research into methods to destroy the slug, including chemicals or using natural enemies.

Critics said a more effective measure was better screening of imported plants to ensure they were not infested. (dpa)