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Oil markets have slumped as mounting worries about a supply glut have pressured crude prices, which have fallen almost 10 percent this week alone.
The dollar gained 1 percent against the crown to trade at 7.8280, close to its peak of 7.8558 hit in December when the crown appeared to be being used as a proxy for the rouble in the midst of Russia's currency crisis.
Fellow oil-producer Canada's currency also suffered on Wednesday, hitting a 5-1/2 year low of C$1.1862 versus its US counterpart.