Google has filed a lawsuit against 'rogue pharmacies' that carry out online sales of drugs illegally to stop such entities from advertising with the Internet major.

The lawsuit comes against the backdrop of rising instances of drugs sold illegally without prescriptions on the Internet.

According to Google, rogue online pharmacies always try new tactics to get around those protections and illegally sell drugs on the web.

"... we (have) filed a civil lawsuit in (US) federal court against advertisers we believe have deliberately broken our rules," Google's Litigation Counsel Michael Zwibelman said in a blog post late Tuesday.

He noted that despite best efforts, a small percentage of pharma advertisements from these rogue companies is still appearing on Google.

Pointing out that there has been a marked increased in the number of rogue pharmacies online, Zwibelman stressed that such litigations should act as a serious deterrent to anyone thinking about circumventing our policies to advertise illegally on Google.

"Rogue pharmacies are bad for our users, for legitimate online pharmacies and for the entire e-commerce industry?so we are going to keep investing time and money to stop these kinds of harmful practices," the blog post said.