It is the latest step in the row between the two since Argentina nationalised energy company YPF, which was majority owned by Spain's Repsol.

EU officials highlighted difficulties with getting export licences as well as rules forcing some companies to import as much as they export.

EU exports to Argentina are worth 8.3bn euros ($10.4bn; £6.7bn) a year.

EU countries import 10.7bn euros of goods and services a year from Argentina.

"Argentina's import restrictions violate international trade rules and must be removed," said EU trade commissioner Karel De Gucht.

An EU statement said: "Argentina appears to issue non-automatic import licences in a discretionary way with burdensome procedures, long delays up to six months and under unacceptable and non-transparent conditions."

The case is not directly linked to the nationalisation of Repsol, but Mr De Gucht said: "The trade and investment climate in Argentina is clearly getting worse."

Last week, Repsol and the investment firm Texas Yale Capital Corp sued Argentina, demanding that it makes an offer for the YPF stake.

The EU is asking for direct talks with Argentina in the first instance. If there is no agreement within 60 days, the WTO will be asked to rule on the issues.