Samsung Electronics Co., the world's biggest technology firm by revenue, estimated its second-quarter operating profit at a sharply lower than expected 7.2 trillion won (US$7.11 billion) on Tuesday amid a slowdown in its smartphone business.

The preliminary estimate represents a 24.4 percent fall from the operating profit of 9.53 trillion won a year earlier, the company said in a regulatory filing. The figure also marks a 15 percent crash from the operating profit of 8.49 trillion won posted during the January-March period of 2014.

It marked the first time for Samsung's quarterly operating profit to fall below the 8-trillion-won mark since the third quarter of 2012, and marks its third consecutive quarter of declining operating profit.

The second-quarter sales were estimated at 52 trillion won, also down 9.5 percent from the 57.46 trillion won a year earlier, according to the company's earnings guidance.

Samsung, the world's top smartphone and memory chip maker, is scheduled to announce its final second-quarter earnings later this month.

Shares of Samsung Electronics closed at 1,292,000 won Monday on the main bourse, down 1.07 percent from the previous session, while the KOSPI shed 0.23 percent. The guidance was released before the local stock market opened on Tuesday. (Yonhap)