With tablet computer sales soaring -- led by Apple's iPad -- a market research company boosted its forecast on Wednesday for shipments of the devices.

International Data Corp. said it expects worldwide tablet shipments of 62.5 million units this year, up from a previous forecast of 53.5 million units.

IDC said tablet shipments rose 88.9 percent in the second quarter over the previous quarter to 13.6 million units and by 303.8 percent year over year.

Apple reported in July that it sold 9.25 million iPads in the quarter which ended on June 25.

IDC said Apple had a 68.3 percent share of the worldwide tablet market in the second quarter, up from 65.7 percent the previous quarter.

The share of the market held by Android-based tablets fell to 26.8 percent in the second quarter from 34.0 percent the previous quarter, IDC said.

Android's drop was due in part to the arrival on the market in the second quarter of the PlayBook from BlackBerry maker Research In Motion, IDC said.

RIM had a market share of 4.9 percent in the second quarter, it said.

"Apple's iOS share will continue to lead by more than 40 percentage points over Google's Android for the remainder of the year," IDC research analyst Jennifer Song said. "But we expect this gap to decrease substantially by the end of our forecast in 2015."

As for electronic book readers, IDC said e-reader shipments were down nine percent in the second quarter from the previous quarter to 5.4 million units while year-over-year growth was 167 percent.

The research firm said Amazon's Kindle grabbed 51.7 percent of the e-reader market in the quarter followed by the Nook from US bookseller Barnes & Noble with 21.2 percent.

IDC said it expects e-reader shipments of 27.0 million units for the year, up from a previous forecast of 16.2 million units.