* EU trade chief: EU states threatened on tariff votes
* Urges EU voting reform to shield EU against pressure
* Voting reform could be decided by this year
By Juliane von Reppert-Bismarck
BRUSSELS, Dec 2 (Reuters) - Some governments threaten EU member states with retaliation unless they back their trade interests inside the bloc, weakening the EU's defences against unfair competition, the bloc's trade chief has said.
The statement was made in a confidential letter to a minister of an EU country, seen by Reuters on Thursday.
"Exports to or investment in the third country are threatened with retaliation if the member state does not oppose (import barriers that would harm the third country)," EU Trade Commissioner Karel De Gucht wrote in September.
De Gucht's warning has stoked debate about reforming EU voting on trade policy to give more power to Europe's central institutions and less to EU capitals.
EU lawmakers and government officials are discussing the reform this week and may agree on it this month.
De Gucht and the reform's advocates -- among them Europe's largest industrial sectors -- say reform is crucial to tempering the power of foreign trading nations to lean on small EU states to influence EU import duties.
"The situation is clearly undesirable both in terms of the effect on member state exports and investment in third countries and in terms of the distortions it brings to EU decision-making on trade defence measures," the letter said.
Greater centralisation of power over the setting of EU import duties "would make member states and their exports and investors far less vulnerable to direct and indirect lobbying".
"LIKE CLOCKWORK"
Reeling from economic crisis, the EU has increased import duties on a slew of products from low-cost exporters, above all China, leading to regular official rebukes from the EU's trade partners but few direct measures of retaliation.
But people familiar with the issue say that behind closed doors, Europe's trade partners regularly lean on individual member states to oppose rises in duties.
"This is not something that happens once or twice, it happens all the time. It's almost like clockwork. Licenses get revoked, imports are delayed, exports are delayed. It makes (EU) member states nervous," said one.
Current EU law gives each European state one vote to decide duty increases. Cast during closed-door meetings, the vote outcomes -- decided on a simple majority principle -- are watched closely by foreign exporters affected by the tariffs.
Votes rejecting duties -- whether or not under foreign pressure -- have resulted in downward adjustments of Europe's defensive duties, or strict time limits being set.
Drafts of the voting reform seen by Reuters would largely eradicate the one-country-one-vote system despite capitals' opposition and hand more power to the Commission.
"Eventually we will have rules in place that will help close the door on this sort of pressure," said Adrian van den Hoven, Director for International Affairs at BusinessEurope, Europe's largest employers' group.
"De Gucht has a point. Many third countries defend their economic interests, and put pressure on member states with threats of retaliation. (Reporting by Juliane von Reppert-Bismarck, editing by Andrew Roche)