BEIJING—Google Inc. Executive Chairman Eric Schmidt said he told North Korean officials that they must drop barriers to global Internet access if they hope to develop their economy.

"As the world becomes increasingly connected, their decision to be virtually isolated is very much going to affect their physical world," he told reporters in Beijing on Thursday, as he returned from a three-day trip to North Korea with former New Mexico Gov. Bill Richardson. He added that it would "make it harder for them to catch...