The Independent Football Regulator (IFR) says it is "in contact" with West Ham and will use its statutory powers to seek "urgent information" from co-owner David Sullivan "relating to his suitability" under its Owners, Directors and Senior Executives regime, after allegations against him.
Multiple women accused the billionaire of abusing his power and preying on them for sex, in some cases when they were in their late teens.
Sullivan "categorically" denied the claims, uncovered by BBC Panorama and the Times.
The Department for Digital, Culture, Media and Sport said the "deeply concerning" allegations must be "treated with the utmost seriousness" and "investigated by the relevant authorities".
The allegations span decades when Sullivan made a fortune from pornography, newspapers and football.
All come from women who were in their late teens or early twenties and were young models seeking work at Sullivan's Daily and Sunday Sport newspapers.
The IFR called the allegations "extremely serious".
It is expected to use its information-gathering powers to determine whether there are grounds for concern regarding Sullivan's role in the club. If the regulator does come into possession of such material, it may open an investigation into the West Ham co-owner's suitability.
Factors the IFR may consider when assessing a person's suitability include whether they have the requisite honesty and integrity.
A Department for Digital, Culture, Media and Sport spokesperson said: "These deeply concerning allegations must be treated with the utmost seriousness and be investigated by the relevant authorities, with victims given the support they need.
"The Government stands strongly against any form of harassment or abuse of power in the workplace and is working across industries to stamp it out and build an environment where people feel safe and able to challenge inappropriate behaviour."
Sullivan stepped down from his role as joint chairman of the football club over the weekend, ahead of the allegations being published on Monday.
In his resignation statement, he said he wanted to focus on fighting "factually incorrect and entirely false, decades-old allegations" concerning his personal life, describing the investigation by Panorama and the Times as "fundamentally unfair".
He said that "after a lifetime spent building businesses in the adult industry in which I have met thousands of women, it is sadly inevitable that a small number of improper conduct claims are being made against me".
West Ham also issued a statement, saying Sullivan had denied any "illegal conduct" and was leaving "in order to avoid disruption to the club while he addresses the matter privately".
The 77-year-old had held the joint chairman position for 16 years, and was the club's largest single shareholder following the death of his business partner, David Gold, in January 2023.
