A few primitive plants producing consumer goods had been built before World War II, but industrial development began only in 1949, when construction was undertaken of a 50,000-kilowatt hydroelectric power station, a textile mill capable of producing 22 million yards of cloth per year, and a sugar mill with an annual capacity of 10,000 tons of sugar. Industrial construction continued under the first and second five-year plans (1951-55 and 1956-60, respectively) during the 1950s, with substantial financial and technical assistance from the Soviet Union. This development was temporarily interrupted in the wake of the political break with the Soviet Union in 1961 but was soon resumed with aid from Communist China (see ch. 6, Government Structure and Political System). The interruption was said by the Albanian leadership to have retarded industrial growth by three years. Disinterested foreign observers, however, reported that the equipment acquired with the aid of Communist China was better suited to the needs of the country and of better quality than that supplied by the Soviet Union. Among the major industrial projects completed or under construction in 1970 with the assistance of Communist Chinese technicians were: copper, chromium, and iron-nickel mines; an oil refinery at Fier with an annual capacity of 500,000 tons of crude oil, a 225,000-kilowatt hydroelectric power station at Vau i Dejes on the Drin River; a 100,000-kilowatt capacity of 500,000 tons of crude oil; a 225,000-kilowatt/thermal power-plant at Fier; a copper-ore dressing installation and a copper-wire drawing mill; a steel-rolling mill at Elbasan; cement mills at Elbasan and Kruje; large textile combines at Tirana and Berat; and a knit goods factory at Korce. Of special benefit to agriculture was the construction of a nitrate fertilizer plant at Fier, a superphosphate plant at Lac, and a plant for the manufacture of tractor spare parts at Tirana. A variety of smaller plants were also built for the production of such items as caustic soda, sulfuric acid, rubber products, electrical equipment and light bulbs, footwear, and vegetable oils. Along with the construction of technologically up-to-date plants, others were built with outdated technology through the lack of construction experience or knowledge of more advanced methods. At the same time, obsolete plants and workshops remained in use. In 1969 these technologically backward plants produced less than half the total output but employed more than half the industrial labor force.