Belgium-Luxembourg Economic Union
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The Belgium-Luxembourg Economic Union (French: Union économique belgo-luxembourgeoise, Dutch: Belgisch-Luxemburgse Economische Unie), abbreviated to BLEU or UEBL, was created by a treaty signed on 25 July 1921 between Belgium and Luxembourg. Expiring in 1972, the initial treaty was extended for ten years in 1982 and again in 1992. On 18 December 2002, the two countries and the three regions of Belgium signed a new convention.
As an economic and monetary union, the economic frontier was lifted and the currencies (Belgian franc and Luxembourgish franc) were set at a fixed parity (though revised in 1935 and 1944). International trade statistics were only available for BLEU as a combined entity until 1999, when European Community rules required split information.
It has been seen as the forerunner of Benelux which also includes the Netherlands.