Korea's top tech firm Samsung Electronics Co. estimated Thursday that its second-quarter operating income increased more than 17 percent from a year earlier on the back of robust sales of its flagship smartphones, such as the Galaxy S7 series.

Operating profit is estimated at 8.1 trillion won ($6.98 billion) in the April-June period, up 17.39 percent from the 6.9 trillion won posted a year earlier, the world's top smartphone maker said in a regulatory filing.

The estimate breaches the 8 trillion-won mark more than two years after it posted an 8.5 trillion-won profit in the first quarter of 2014, and is far above the previous market forecast.

Market consensus for the operating income of Samsung for the April-June period was at 7.32 trillion won, according to data compiled by industry tracker FnGuide.

Samsung said its second-quarter sales are also forecast to have reached 50 trillion won, also up 3 percent from 48 trillion won a year earlier.

Samsung did not offer a net profit estimate for the second quarter. Its finalized earnings will be announced later this month.

The better-than-expected earnings estimate was the result of its flagship smartphone business division scooping up huge profit.

Market analysts estimated that the tech behemoth raked in at least 4 trillion won in operating profit solely from its information technology and mobile business division, one of the company's main revenue sources.

Some analysts even forecast up to 4.5 trillion won in operating profit from the division.

Samsung did not release detailed figures for each business division in Thursday's earnings guidance report.

The mobile division posted an operating profit of 3.89 trillion won during the January-March period of 2016.

Market experts estimate that Samsung's combined shipments of the Galaxy S7 and S7 Edge -- its two flagship models -- hovered at some 15 million units in the April-June period. Noticeably, the sales of the Galaxy S7 Edge, which is more expensive, might have beaten out the Galaxy S7, according to the sources.

The two latest models, first showcased at a trade fair in Spain in February, come with improved batteries and are water and dust resistant. The company also brought back the micro SD card slot that had disappeared in the Galaxy S6 series.

Experts also attributed the improvement in the division's profitability to the company's streamlined budget smartphone models -- the A and J series.

Samsung Electronics sold 81.18 million smartphone units around the globe in the January-March period, bolstered by the early release of its flagship Galaxy S7 series in late March.

Samsung's consumer electronics business is also estimated to have more than 1 trillion won in operating profit for the April-June period on the back of robust sales of SUHD TV series that applied the so-called quantum dot technology in the North American market, the analysts said.

A quantum dot refers to a form of semiconductor that is 10,000 times finer than a human hair and improves the brightness, visibility and power efficiency of displays.

The division posted an operating profit of 510 billion won in the first quarter of this year.

The company's chip business, which emerged as the new main source of profit last year amid poor smartphone sales, is also forecast to post an operating profit of some 2.5 trillion won, analysts said.

Samsung display division, which also makes organic light-emitting diode (OLEDs) panels, is also expected to bring in a profit of about 200 billion won during the first quarter, a turnaround from a loss of 270 billion won the previous quarter, the analysts said.

More smartphone makers are forecast to adopt the OLED panels to replace liquid crystal display ones. Apple Inc. and other smartphone makers are moving to equip their smartphones with OLED display panels.

A report by industry tracker IHS shows that the global shipments of OLED display panels are expected to soar to 630 million units in 2019 from 250 million in 2015.

Shares of Samsung Electronics traded at 1,441,000 won as of 10:30 a.m., up 1.41 percent from the previous session's close. The guidance was released before the local stock market opened Thursday. (Yonhap)