(Reuters) - Starbucks Corp said it will launch its own single-cup coffee and espresso drink machine later this year, putting it in direct competition with partner Green Mountain Coffee Roasters Inc, seller of the popular Keurig home brewers.

Shares of Green Mountain were trading down nearly 14 percent at $53.92 in after-hours trade. They had earlier plunged 24 percent, but regained some ground after Starbucks said on a conference call that it would continue to supply Green Mountain with Starbucks-branded single-serve coffee pods called K-cups.

Starbucks shares rose over 4 percent to $52.45.

Starbucks said that the "Verismo system by Starbucks" will make both brewed coffee and espresso beverages such as lattes.

The system will be sold online at select Starbucks shops and at specialty retailers in the United States, Canada and some other international markets, it said.

Pricing on the machine will not be announced until closer to launch, Starbucks said. Existing machines now start at about $50 but can cost as much as $800.