The output of China's steel industry slowed significantly in the first three quarters of 2012, according to data provided by the country's top economic planner on Sunday.

Crude steel production increased by only 1.7 percent year on year from January to September to reach 542.34 million tonnes, retreating 9 percentage points from the same period last year, the National Development and Reform Commission (NDRC) said in a report on the steel industry.

The steel and iron industry has been mired in a slowing economy that expanded 7.7 percent year on year in the first three quarters, with the industry's combined profits plunging 53.4 percent from the previous year to 82 billion yuan (13 billion U.S. dollars) in the January-August period, according to the NDRC data.

Steel prices were still on the decline as of the end of September, with the steel price composite index falling by 3.92 points to 100.47 points.

However, China's steel output was still more than twice that of the rest of the world last year, further consolidating its position as the world's largest steel producer.

The NDRC data showed that China imported 550.76 million tonnes of iron ore, up 8.4 percent year on year from January to September, while exports of steel products rose 10.2 percent from the previous year to 40.94 million tonnes.