LUXEMBOURG (Reuters) - The European Union banned the sale of oil and oil products to North Korea on Monday, in a largely symbolic move aimed at encouraging countries that have more significant levels of trade with the country to follow suit. EU foreign ministers also imposed a blanket ban on doing business with North Korea in sanctions that go beyond the latest U.N. measures. The EU does not sell oil to Pyongyang.  Following North Korea s most powerful nuclear test, the U.N. Security Council capped North Korean imports of crude oil, but China and Russia resisted an outright ban. EU ministers cited  the persistent threat to international peace and stability  posed by Pyongyang. As part of the measures, North Korean workers in the EU - estimated to be about 400, mainly in Poland - now face a lower limit on the amount for money they can send home and their work visas will not be renewed once they expire.  The sanctions add three more top North Korean officials and six businesses to a blacklist banning them from travel to the EU and freezing their assets.  That will take the total of those sanctioned by the EU to 41 individuals and 10 companies, a senior EU official said. U.N. sanctions target 63 people and 53 companies and institutions.        