The European Commission warned eight developing countries Thursday of sanctions if they did not do more to stop "criminal" illegal fishing, saying it was taking the first step of its kind.

The Commission said it did not plan to impose penalties as yet on Belize, Cambodia, Fiji, Guinea, Panama, Sri Lanka, Togo and Vanuatu, but stressed they could face a ban on the sale of fishing equipment, for example, failing action.

"This is not a black list but a yellow card," European maritime affairs commissioner Maria Damanaki said in a statement.

"We want these countries as partners ... but we also want to signal to the world that the EU will not tolerate (illegal) fishing -- a criminal activity which undermines the livelihood of fishing communities and depletes fish stocks.

"It must be eradicated by all means," Damanaki said.

The eight nations have been informed and given "a reasonable time" to respond and take action, the statement added.

Asked at a press conference what the next step might be, Damanaki said: "If they are cooperative, fine; if not, the European Commission will propose measures, trade measures.

"The next time it will not just be a yellow card ... it will be painful for everybody," she said, noting that Indonesia had been working with the EU for about a year and so was not included on the list issued Thursday.

The EU, the world's biggest importer of fish, adopted an 'Illegal, Unreported and Unregulated' directive in 2010, aiming to close the market to those who flout its rules.

Damanaki said illegally caught fish account for nearly 20 percent of the global total.