SAN FRANCISCO  — A judge late Tuesday ordered Samsung Electronics Co. to halt sales of its Galaxy 10.1 tablet computer while the court considers Apple’s (Nasdaq: AAPL) claim the South Korean tech giant illegally copied the design of the popular iPad.

U.S. District Judge Lucy Koh said Apple Inc.’s lawsuit appeared likely to prevail.

“Apple has established a strong case on the merits,” Koh said.

Koh had earlier said the two products are “virtually indistinguishable,” but she declined in December to take the dramatic step of prohibiting sales of the Galaxy 10.1. She changed her mind after the U.S. Court of Appeals for the Federal Circuit told Koh to take another look at Apple’s request for an injunction, ruling June 19 that it appeared the Cupertino-based company had a strong case. The Washington, D.C., court handles most patent appeals.

“Although Samsung has a right to compete, it does not have a right to compete unfairly, by flooding the market with infringing products,” Koh wrote in her Tuesday order. She said Apple would be “irreparably harmed” if sales of the Galaxy 10.1 continued.

The world’s two biggest makers of high-end phones have accused each other of copying designs and technology for mobile devices and are fighting patent battles on four continents to retain their dominance in the $219 billion global smartphone market.

South Korea-based Samsung will take necessary legal steps in response to Tuesday’s ruling on the year-old model, the company said in a statement today.

“This is an extension of their fight in the smartphone space,” Kim Young Chan, a Seoul-based analyst at Shinhan Investment Corp., said by phone. “If you look at precedents, different cases yielded different rulings. As long as smartphones aren’t blocked, Samsung’s fundamentals will stay intact.”

Quarterly sales of the Tab 10.1 in the U.S. may total about 300,000 units on average, Kim said. Samsung, which doesn’t disclose shipment figures for smartphones and tablets, sold 44.5 million smartphones globally in the first quarter, according to market researcher Strategy Analytics. Apple is also the biggest buyer of Samsung chips and displays.

Koh ordered Apple to post a $2.6 million bond in case it ultimately loses the case.

The ruling is a small part of a much larger patent battle between the two tech giants, who are scheduled to go to trial next month in San Jose.

Apple filed its lawsuit last year, and the two companies are enmeshed in patent disputes around the globe revolving around smartphones and handheld computers. Samsung, with its Android-powered products, has emerged as one of Apple’s chief rivals.

Apple also accuses the South Korean company of infringing patents related to the iPhone. Apple is seeking a similar injunction barring Samsung from selling one of its smartphones in the United States.

(The AP and Bloomberg contributed to this report.)