Many political ads running on Facebook in India during its current election season are backed by organizations that hide their identity, according to civil society groups and recent studies, threatening the integrity of a process intended to enforce transparency in a system full of emotional appeals.

The world’s largest election and one of its most expensive, India’s voting season began last month and runs through June 1. Facebook has hundreds of millions of users in the country, which is the social network’s largest market, and is reaping a significant portion of an estimated $16 billion in campaign spending.