Nato is using information gleaned from Twitter to help analysts judge which sites could be targeted by commanders for bombing and missile strikes in Libya.

Potentially relevant tweets are fed into an intelligence pool then filtered for relevance and authenticity, and are never passed on without proper corroboration. However, without "boots on the ground" to guide commanders, officials admit that Twitter is now part of the overall "intelligence picture".

They said Nato scooped up all the open source information it could to help understand Gaddafi, who is constantly changing his tactics and concealing himself – and his forces – in places such as schools and libraries.

"We take all sorts of information, but we can't act on a single source," said a Nato official. "It helps draw our attention to certain areas of the country where we see Gaddafi forces.[That] allows us to take action."

The official suggested the sheer size of Libya made it difficult to get a full picture of what was happening across the country.

He said the organisation monitors Twitter feeds from Tripoli and other places for "snippets of information". These could then be tested, corroborated or not, by Nato's own sources, including direct lines of communication with the rebels, and imagery and eavesdropping from Nimrod spy planes. Nato is also aware that Gaddafi might be using Twitter to feed false information. "We have to be careful it is not used for propaganda [by Gaddafi's forces]," the Nato official said.

Wing Commander Mike Bracken, another Nato spokesman, confirmed Twitter was being monitored.

"Any military campaign relies on something that we call 'fused information'," he told a briefing. "So we will take information from every source we can. And if we get information from a press conference in Rome or we get information from somebody passing secondhand, we'll get information from open source on the internet, we'll get Twitter, you name any source of media and our fusion centre will deliver all of that into useable intelligence.

"The commander will assess what he can use, what he can trust, and the experience of the operators, the intelligence officers, and the trained military personnel and civilian support staff will give him those options. And he will decide if that's good information, I'm going to act on it. Where it comes from, again, it's not relevant to the commander. He will use all that is available to deliver his mission."

Nato, he said, was being astute and would "take information from any source it can. The role of the intelligence officers and the personnel who work in headquarters here and in the other Nato headquarters is to fuse all of that information together and then provide the commander the best situation awareness he can be given.

"Let's be quite clear, Nato does not have boots on the ground."

The Ministry of Defence said it was normal military practice to gather all sources of open source information and that tweets from people in cities such as Misrata and Benghazi would be thrown into the intelligence mix.

"All this material is brought together and the intelligence analysts then have to decide what weight to put on them," said a spokesman. "You would never act on one single source of intelligence, but Twitter can contribute to the overall intelligence picture."

The Guardian reported earlier this month that former SAS soldiers and other western employees of private security companies are helping Nato identify targets in the Libyan port city of Misrata. Special forces veterans were passing details of the locations and movements of Gaddafi's forces to the Naples headquarters of Lieutenant General Charles Bouchard, Canadian commander of Nato forces, official sources said. The targets are then verified by spy planes and US Predator drones.

"One piece of human intelligence is not enough," a source said. "The former soldiers are there with the blessing of Britain, France and other Nato countries, which have supplied them with communications equipment."