Samsung Electronics Co., the world's largest technology firm by revenue, on Friday fuelled concerns about flagging demand for high-end smartphones with a weaker-than-expected earnings forecast for the second quarter.

Samsung's forecast of 9.5 trillion won ($8.3 billion) in operating profit for the April-June quarter would be a record for the South Korean company. But analysts had expected a figure of more than 10 trillion won, and Samsung shares lost more than two percent in morning trade.

"Demand for high-priced, high-end smartphones shows slowing growth, which could hurt Samsung's profit margin," IBK Investment and Securities analyst Lee Seung-Woo told the Yonhap news agency.

Samsung has lost nearly 30 billion dollars in market value since mid-March, before it launched the Galaxy S4 smartphone a month later. Several brokerages have downgradedSamsung and their earnings forecasts for the company on fears that the S4 is not selling as strongly as hoped.

"Its hefty marketing spending on the Galaxy S4 might have dented its mobile business's performance, but its semiconductor and display units are projected to have produced good results," said Kim Young-Chan, an analyst at Shinhan Financial Investment.

Samsung, the world's top maker of smartphones, memory chips and flat-panel TVs, was giving earnings guidance before official results at the end of July.

The estimate for second-quarter operating profit represents a 47 percent increase from the actual figure of 6.46 trillion won a year earlier.

The forecast marks an 8.2 percent rise from the previous quarter, when the tech behemoth posted an operating profit of 8.78 trillion on the back of robust smartphone sales.

The company did not provide a net profit estimate in the earnings guidance or break down figures for its individual business units.

Sales in the April-June period were expected to reach 57 trillion won, up 19.8 percent from the same period last year.

A poll of seven analysts forecast an average second-quarter operating profit of 10.1 trillion won on sales of 58.6 trillion won, Dow Jones Newswires said.

In morning trade in Seoul, Samsung shares were down 2.58 percent at 1.28 million won.

The new market jitters about Samsung come after Canada's troubled BlackBerry, fresh after launching two flagship phones, on Friday posted an unexpected first-quarter loss and disappointing sales figures. Its share price tumbled nearly 28 percent on the news.

Shares in Apple Inc. are well off their historic highs, having taken a beating earlier this year on concerns that demand for the iPhone 5 may be tapering off.

The mobile business, a key profit driver for Samsung, accounted for 74 percent of its total operating profit in the first quarter. Samsung also makes consumer electronics including cameras and laptops, and home appliances.