The U.S. government expressed displeasure Thursday over a planned trip by Google Chairman Eric Schmidt to North Korea, saying especially the timing is not "helpful."

The State Department confirmed that it is "obviously aware of the trip" by Schmidt and former New Mexico Gov. Bill Richardson, who has close personal ties with the communist nation.

"Frankly, we don't think the timing of this is particularly helpful, but they are private citizens and they are making their own decision," department spokeswoman Victoria Nuland said at a press briefing.

Schmidt and Richardson are "well aware of" the U.S. government's view, she added.

Nuland cited North Korea's long-range rocket test in December, which the U.S. regards as a clear violation of U.N. resolutions prohibiting Pyongyang from using ballistic missile technology.

She said the two will neither be accompanied by U.S. officials nor carry U.S. government messages.

A South Korean diplomatic source said the U.S. figures are expected to fly to Pyongyang as early as next week.

It would mark the first trip by a top Google official to the secretive nation, which strictly controls the flow of information.

The purpose of their visit remains unclear. Google has not responded to any related media inquiry.

Nuland would not tie the duo's upcoming trip with an effort to win the release of a detained Korean-American citizen.

"Again, they are not going on our behalf," she said. "No American official is going with them. They are not carrying any messages from us."

She said the Swedish Embassy in Pyongyang is in contact with the detained man, Kenneth Bae, on behalf of Washington.

The U.S. has no diplomatic ties with North Korea.

"They have been granted consular access to him, and they are providing all appropriate consular assistance," Nuland said.

Her comments mark a contrast to media speculation that the U.S. government may be supporting the trip by those private envoys in hopes of a breakthrough in the campaign to win the release of Bae.

When asked if Google, a California-based internet search provider, can do business in North Korea despite a wide web of U.S. sanctions on the country, Nuland was skeptical.

"All U.S. companies are subject to the U.S. sanctions regime with regard to the DPRK (North Korea)," she said.

Experts said the Google chairman's visit to North Korea might be related with a stated push by its leader Kim Jong-un for economic development.

"A quick read of Kim Jong-un's New Year's speech reveals that he is stressing the economy and science and technology," said Ken Gause, a senior research analyst with CNA Strategic Studies'

International Affairs Group. "It seems that this visit could potentially resonate on both these levels."

Kim is keen to show that North Korea is modernizing and there is no better way to do this than to engage with a high tech company like Google, added Gause.

An informed source here, however, would not attach excessive meaning to Schmidt's move.

"The 12-member economic delegation from North Korea visited Google Headquarters in spring 2011. So, this is not the first contact between the North Korean authorities and Google, and, I am sure, not the last one," the source said, requesting anonymity. (Yonhap News)