NSA Shivshankar Menon has taken up with US ambassador Nancy Powell the issue of secret surveillance of Indian citizens by Americas National Security Agency. New Delhi,which has termed as unacceptable the violation of domestic privacy laws,is learnt to have taken up the matter early this week. The issue has been mentioned to the US ambassador. Our interest is in knowing little bit more. What actually has transpired, an official source said. The Americans have said they are still doing the assessment to see what amount of damage in terms of their data has been done and,therefore,are not in a position to say much,the sources added. The sources said once the US gives more information,only then can the government evaluate the situation and examine what laws were violated.