Eric Schmidt, Google's executive chairman, has used a private visit to the country to urge North Korea to allow its citizens to use the internet or risk staying behind economically.

Schmidt joined Bill Richardson, the former governor of New Mexico, as part of a US delegation whose four-day visit was not sanctioned by Washington.

Speaking at Beijing airport on Thursday at the end of the trip, Schmidt said: "As the world is becoming increasingly connected, their decision to be virtually isolated is very much going to affect their physical world, their economic growth and so forth.

"[The government] has to make it possible for the people to use the internet. It is their choice now. It is, in my view time, for them to start or else they will remain behind."

Use of the internet is severely restricted in North Korea and most users are only able to access a national intranet rather than the world wide web

Richardson said the the delegation had urged Pyongyang to halt all missile and nuclear tests, which have incurred UN sanctions, and sought fair treatment for a US citizen who has been detained in North Korea.

Kenneth Bae was detained in the country in November for unspecified crimes against the state.

Richardson said he was unable to meet Bae, and had expressed his concerns to authorities who had assured him of Bae’s good health.

The former governor said that the main success of the controversial visit was Schmidt's efforts for greater adoption of the internet.

'Sightseeing trip'

Emma Campbell, a Korea Institute fellow at the Strategic and Defence Studies Centre at the Australian National University, told Al Jazeera that at first Schmidt's visit looked like a "sightseeing trip with this added agenda of trying to free the American who had been detained over there".

"But, if one of the results of the trip is that North Koreans [receive] better access to the internet and better communications infrastructure, I think that will be a very positive outcome," she added speaking from Canberra.

The US State Department has called the timing of the visit by Scmidt and Richardson "unhelpful" as it appeared to hijack US diplomacy.

North Korea's continuing development of nuclear testing facilities and missiles has prompted sanctions by the UN.