Samsung Electronics has reported a record quarterly profit, but its shares tumbled on doubts its mainstay smartphone business can maintain rapid growth.

The telecom giant estimated its April-June operating profit at a record high of 9.5 trillion won ($8.3 billion). That is a 47 per cent jump from a year earlier and 8pc growth from the previous quarter.

But it fell short of forecasts by analysts who held higher expectation for the world's largest smartphone maker.

Analysts surveyed by FactSet, a financial data provider, forecast operating income of 10.2trn won on average. Samsung shares dropped nearly 4pc in Seoul.

Samsung said sales grew 20 per cent to 57trn won ($50bn).

Sales of the latest iteration of Samsung's flagship smartphone, the Galaxy S4, hit 10 million units in May, less than a month since its debut. Sales of the S4 hit the 10m mark about 20 days faster than the previous model.

Analysts say high marketing costs probably weighed on Samsung's mobile business despite the robust sales in the first month.

"Because of the marketing costs, the telecommunications business was probably weaker than expected," said CW Chung, an analyst at Nomura Financial Investment in Seoul. "Semiconductor and other businesses seem to have improved from the previous quarter."

The popularity of Galaxy smartphones has fuelled Samsung's year-long string of record quarterly earnings.

But worries have emerged that Samsung's profit growth will slow as developed countries, which are the biggest buyers of high-end phones, near a smartphone saturation point.-Reuters