The environmental group Greenpeace launched a campaign on Tuesday against 20 European "monster boats" it says use a range of tricks to dangerously overfish the world's oceans.

"Our oceans and fish stocks are in deep crisis with too many large and destructive vessels chasing too few fish," Greenpeace said in a summary of its report entitled "Monster Boats; The Scourge of the Oceans".

Among the targeted boats are five Spanish-flagged vessels, including two that belong to the Spanish fishing giant Albacora S.A.

Four other vessels in the cross-hairs are owned by the Netherlands firm Parlevliet en Van der Plas BV, one of which flies a Dutch flag, two of which fly a German flag and the last a Lithuanian flag.

Greenpeace also highlighted vessels flying the flags of Portugal, Sweden, France, Denmark, Britain, and Poland.

The report shows "how a number of industrial fishing barons recklessly use a wide range of ruses" to bend rules and gain maximum profits.

The tricks include "frequent flag changes... the use of front companies and tax havens and taking advantage of personal connections to decision-makers," it said.

The 20 vessels contribute mainly "to stock depletion" at the expense of "the social, economic and cultural fabric and sustainable development of coastal communities in Europe or elsewhere," it said.

It accused EU fisheries ministers and other decision-makers around the world of failing to act and stop overfishing.

It suggested that the vessels violate new EU rules specifying that "governments should promote responsible, low-impact fishing".

The fishing lobby group Europeche denounced the campaign as "typical Greenpeace hysteria," according to a statement from its President Javier Garat.

"The assumption that small is beautiful and big equals bad is wrong," Garat said.

"A high number of smaller vessels could also hypothetically flout the rules, overfish and do huge damage to fish stocks and the environment. At the same time, bigger vessels can also be perfectly sustainable," he said.

Garat added that size does not matter "if the healthy fish stocks are targeted and appropriate techniques are applied, as is the case with all EU vessels."