The Swiss authorities are investigating reports of illegal spying activities by the United States mission to Geneva.
The justice ministry confirmed that it called on Washington to stop its surveillance detection programme aimed at spying on people who are near official US buildings.
The Swiss government had rejected a request for surveillance activities by the Geneva mission in 2007, a ministry spokesman said.
He added that there are indications that the mission continued the programme.
The US embassy to Switzerland denies any wrongdoing, according to the NZZ am Sonntag newspaper.
The non-profit media organisation, WikiLeaks, revealed that specialists in the US Geneva mission were spying on a couple, considered a terrorist threat, back in 2005.
Similar spying accusations have also been leveled at US missions in Norway.
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