HONG KONG (AFP) - Apple and Samsung have overtaken long-time leader Nokia for the top two spots in the global smartphone market, a report said Friday, underscoring the Finnish handset maker's ongoing struggles.

US-based research firm Strategy Analytics said the US and Korean smartphone makers outpaced Nokia in the second quarter, with the sector posting record quarterly shipments of 110 million units, or a 76.3 percent year-on-year rise.

"Just four years after the release of the original iPhone, Apple has become the world's largest smartphone vendor by volume," the report said.

The US company's global market share grew to 18.5 percent, up from 13.5 percent last year, and propelling it to top spot in the smartphone market, Research Analytics said.

"Apple's growth remained strong as it expanded distribution worldwide, particularly in China and Asia," it added.

Samsung's smartphone market share in the second quarter jumped to 17.5 percent from five percent a year earlier, making its the world's second-biggest smartphone producer, the report added.

Nokia's market share meanwhile slumped to 15.2 percent from 38.1 percent during the second quarter last year, it said.

"This is a tough year for the company," Nokia spokesman Doug Dawson told AFP on Friday.

In terms of volume, Samsung sold 19.2 million smartphones in the second quarter, a whopping 519 percent increase from the second quarter in 2010.

Apple took the top slot with 20.3 million smartphones sold, with Nokia surrendering the lead for the first time with just 16.7 million smartphone sales.

Last week, Nokia reported only its second quarterly loss since 1998 with a shortfall of 368 million euros ($525 million), compared with a net profit of

227 million euros one year earlier.

On Wednesday, ratings agency Moody's downgraded Nokia's debt by two notches, citing the firm's lost market share. Moody's also said it was giving the new rating a negative outlook, meaning that it might lower it further.

"We're in a transition, but it's a necessary one to put down the foundation for a stronger Nokia," Dawson said.

Nokia's fortunes have been in a tailspin since February, when chief executive Stephen Elop, who had run the company for less than half a year, launched a radical strategic shift which included abandoning Nokia's smartphone platform Symbian in favour of a tie-in with Microsoft.

While admitting that the transition would be a rocky one, Nokia is gambling its future on the hope that in 2012, they can begin clawing back lost market share when the first Microsoft phones begin shipping in volume.