Chinese excavator maker Sany Heavy Industry Co Ltd's export sales surged 50 percent between January and September versus a year ago, while domestic sales were flat in the same period, Vice-President He Dongdong said on Tuesday.

"Our company's exports are quite good during the period of January to September. Exports were up 50 percent from January to September," he said on the sidelines of a conference in Beijing.

Domestic market conditions had deteriorated for the entire industry sector, but sales at Sany, China's largest construction machinery maker, had outperformed the broader market, the executive added.

"The whole (heavy machinery) industry slid about 20-30 percent, but our company's domestic sales are flat compared with last year. We are running ahead of the industry. But compared with years of high growth, our growth this year has slowed down", He said.

In August, the firm missed analyst forecasts with a 28 percent fall in second-quarter net profit, its biggest quarterly profit drop since 2008, as China's economic slowdown led to a jump in unpaid bills.

The outlook for the industry has been further clouded by a mountain of unsold equipment left over after a four-year construction boom fuelled by China's massive 2008 stimulus program.

Caterpillar Inc, the world's largest maker of tractors and excavators, slashed its own 2012 forecasts on Monday and noted that sales in China had declined in the quarter and had yet to improve.