Enterprise Inns asked MPs investigating the industry to warn licensees about the "risk" of taking advice from trade union the GMB.
In supplementary evidence given to the Business, Innovation and Skills committee, it emerged the Solihull-based company asked the committee to use its "status" to speak out against the union.
The GMB weighed in on the beer tie debate last year - and is currently threatening a national ballot on strike action against the pubcos.
Some have questioned the GMB's motives for getting involved in the industry - and whether it can effectively represent the interests of self-employed people.
Enterprise's evidence said: "Anything your committee can do to highlight your concerns as to the advice being provided by GMB would, I believe, be extremely valuable to tenants and lessees…and I hope that you will be able to use the benefit of your committee's status to provide timely guidance and advice to licensees who are potentially at risk of following GMB advice."
Enterprise also branded the GMB's advice, which included stating that Parliament had given legal immunity to licensees involved in trade disputes, as "deeply disturbing and seriously irresponsible" and described its activities as "sinister".
No direct mention was made of the GMB in the main section of the BIS committee's report, published yesterday.
However the committe did speak out against an "anti-tie campaign" in which licensees are encouraged to break the tie.
The report said: "This campaign encourage licensees to break their contract and therefore open themselves up to legal action. We have articulated our reservations about the tie on a number of occasions but this is not the way to proceed.
"It will only serve to harm those lessees who take part in the campaign."