SAN FRANCISCO, Jan. 22 -- U.S. top coffeehouse chain operator Starbucks Coffee Company (Starbucks) on Tuesday formally began delivery service of coffee, beverage and soft drinks, as well as food items in San Francisco, the company said.

Starbucks said the pilot program, which was in partnership with Uber Eats, will be expanded to other stores in Boston, Chicago, Los Angeles, New York and Washington, D.C., in the coming weeks after an initial test in Miami.

With San Francisco as the first city where the delivery service was launched, the Seattle, Washington State-based company's food program, Starbucks Delivers, will be available in seven U.S. cities this spring, Starbucks said.

Starbucks started the test program in Miami in the fall of 2018, which was powered by Uber Eats. It "saw strong demand, including repeat business throughout the day and positive feedback from customers," said the company.

The U.S. expansion of Starbucks Delivers coincided with its another new pilot to be launched later this month, when London is to be selected as the first European city to use Starbucks Delivers, which will also be powered by Uber Eats.

"We know we have untapped customer demand for Starbucks Delivers in the U.S. and starting today, we're expanding our best-in-class experience to our customers both in and out of our stores," said Roz Brewer, group president and chief operating officer for Starbucks.

When the program is fully rolled out, delivery will be available from about one-quarter of Starbucks stores in the United States, which amounts to about 3,500 branches.

Starbucks is now offering delivery services in the company's 11 global markets and expects to unveil delivery pilots in other countries this year.

The global online food delivery market currently represents a 95-billion-U.S.-dollar opportunity and is projected to grow by more than 11 percent annually through 2023, said the U.S. coffee powerhouse.

Starbucks Delivers was first announced in August 2018 in China through a partnership with the country's largest e-commerce retailer Alibaba and on-demand food delivery service Ele.me.

Starbucks has expanded its delivery services to about 2,000 stores across 30 cities in China, the world's second largest economy.

While Starbucks is introducing delivery services to select stores in Japan's Tokyo and the U.S. city of Miami, it is expanding its global markets that also include China's Hong Kong, Singapore, Indonesia, Vietnam, Mexico, Colombia and Chile.