OSLO, July 25 (Xinhua) -- Researchers claim that Facebook was a key tool when the Norwegian Directorate of Immigration (UDI) decided whether some foreigners will lose their residence permit in Norway, newspaper Aftenposten reported Wednesday.

In a new report ordered by the UDI itself, the Institute for Social Research (ISF) went through a selection of UDI cases to see on what grounds residence permit has been revoked.

The researchers have undergone 72 cases that ended with revoke of residence permit, and in 20 of these, investigation of Facebook accounts were a part of the information retrieval, the report said.

Information from Facebook and other social media together with copies of money transfers abroad, assessment of language and dialects or contradictions in the foreigner's self-introduction were important parts of many investigations.

The information was used to reveal whether a foreign national had provided incorrect information about his or her home or place of residence.

"All of these tracks make Facebook a useful tool for verifying or reversing a suspicion. However, in some cases, information from Facebook is used as the only new moment to be the basis for the revocation decision. This we see as problematic," said ISF researcher Jan-Paul Brekke.

The ISF researchers believe it is unfortunate that those who are subject to social media investigations are not informed on the UDI's guidelines, Aftenpostem wrote.

"It weakens foreigners' legal right and ownership of private information. But we also see the disadvantages. If the authorities went public, that will enable strategies where foreigners adapt their social media presentations to such guidelines," Brekke said.

According to Hanne Rygh Holter, UDI's press adviser, more guidelines have been prepared to ensure that work is carried out in accordance with laws and regulations and a public version of guidelines will replace the internal ones.