Media playback is unsupported on your device Media caption Many landmarks are now labelled including notorious prison labour camps - Courtesy Google Maps

Google has puts its first detailed maps online of North Korea, a country that has so far been mostly blank on the search giant's popular Maps website.

The data was compiled on Google's Map Maker tool, which allows users to contribute information mainly using satellite images or local knowledge.

Many landmarks are now labelled, as are the notorious prison labour camps and nuclear research sites.

The move comes a few weeks after the head of Google visited North Korea.

In the capital, Pyongyang, schools, theatres, government buildings and underground stops are now marked in Google Maps, as are statues, some embassies, an ice rink and the infamous 105-storey Ryugyong hotel, which has been under construction for more than 25 years.

The Yongbyon nuclear site is labelled, to the north, and a road called Nuclear Test Road, leading to a site north of Punggye-ri which is believed to be where Pyongyang is preparing to test a nuclear device.

Image caption The Yongbyon nuclear site and a plutonium separator facility have been labelled

There is little detail of much of the country but a number of grey sites are marked as being some of the many prison labour camps in North Korea, which some 200,000 people are thought to be held.

In the largest camp - Camp 22 - near the border with China, the map identifies an armoury, a food factory and a guard's rest room.

BBC technology correspondent Mark Gregory says the information given by the maps is likely to be of particular interest in South Korea, where many people have ancestral connections or family still living in the North.

But the citizens of North Korea itself will get little benefit from it, he adds, as only a few hundred are allowed access to the internet by their government.

A number of other detailed maps of North Korea are also available online, including the Digital Atlas on 38North, a website run by the US-Korea Institute at Johns Hopkins university.

Scant information

Launched in 2008, Map Maker data has been used to build maps in Google Maps for countries such as Iraq and Afghanistan.

The process uses data sent in by members of the public which are then fact-checked. In the case of North Korea, Google said satellite images were the main source.

"For a long time, one of the largest places with limited map data has been North Korea. But today we are changing that," said Jayanth Mysore, senior product manager at Google Map Maker.

"As a result, the world can access maps of North Korea that offer much more information and detail than before," he said.

Google said a large number of people in South Korea had contributed information to create usable maps.

However, at least one of the contributors was from Australia, and does not speak Korean.

Image caption The guards' restroom and the director's office are included on the map of forced labour camp, Camp 22

"I wanted to go to North Korea and because it was not yet mapped I decided to start mapping so I could at least see how easy it would be to travel within the country," Sebastiaan van Oyen, who works as a risk manager for a financial trading firm in Sydney, told the BBC.

Mr van Oyen said he had used satellite images to get his data saying they "are good enough to cover the whole country, although the quality and date of the data varies".

"For a basic map you will be fine, but it will take time to get reliable street level navigation."

However, he said that the biggest obstacle towards creating a more detailed map was to get enough local knowledge to name all the features.

"Keep in the back of your mind that there are restricted areas and not much [readily available] local knowledge outside of the Democratic People's Republic of Korea."

Google's Chairman, Eric Schmidt, visited North Korea earlier this month, despite warnings from US leaders that it was "ill-advised" in the wake of Pyongyang's launch of a long-range rocket in December.

Mr Schmidt urged the country to end its self-imposed isolation and allow its citizens to use the internet, saying it would lag behind economically unless it embraced internet freedom.