Rashtriya Swasthya Samiti — FAKE OFFER LETTER

sir i applied for the post of LAB TECHINICIAN in the RASHTRIYA SWASTHYA SAMITI by watching the advertisement in the ANANDA BAZAR PATRIKA 14 th April 2015 that the advertisement is like this RASHTRIYA SWASTHYA SAMITI(central govt.department under ministry of health).now i got the offer letter for the employement for LAB TECHINICIAN ON 8 th june .In that they said i should pay an amount of rs.5250 as a membership Joining Fee on demant draft on "RASHTRIYA SWASTHYA SAMITI" payable at kolkata.to get the training pass letter for the training. i would like to know whether it is central government department or not. i want to get all the last recruitement details of it for the same post.In the website : Rashtriya Swasthya Samiti : it is central goverment registered. how can we know whether it is corrcect one or fake.please watch the website and provide the reality of this.