SEBI last year imposed a quota of one female director on the board of every listed firm. It extended the deadline once last year, but despite last-minute appointments, hundreds of firms, including several large state-owned companies, still fall short of the requirement.
"I find it very shameful that in this country, about 8,000 or 9,000 listed companies can't find even one woman who is competent enough to be on their board," SEBI chairman U K Sinha told reporters.
"I'm very categorical: if people do not follow it willingly, then it will have consequences. And the consequences will be as per the law and can be very serious."
He did not specify the penalty or consequence.
According to data combined by Prime Database, almost one third of companies listed on the National Stock Exchange still have no women directors on their board. Laggards include state owned oil firm ONGC
That is an improvement from early 2014, when the rule was introduced. In February last year, two-thirds of firms lacked a single female director.
But campaigners argue that the last-minute rush has also brought in female directors who do not meet the spirit of the law, as they are connected to the "promoters", or majority shareholders -- in many cases, through family.
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According to Prime Database, if the requirement was for boards to have independent women directors, 62 percent of listed firms would fall short.
Poonam Barua, an economist and a campaigner who runs WILL Forum India and helps promote women in leadership, said there was no issue of supply of qualified women among India's roughly 600 million women, or any shortage of ambition.
Instead, she argues companies themselves have been reluctant to accept different voices.
"I understand the rest of the world has the same problem, the difference is we have 500 million women. We are 8 percent of the world population," Barua said.
"If in 8 percent of the world's population you cannot find qualified women, I say go and change your perspective."