Locally-listed Osim International announced that a second writ of summons has been issued against it by The Wellness Group and its chairman, Mr Manoj Mohan Murjani.
In a statement to Singapore Exchange on Tuesday, Osim said that the latest document alleges that the company and its directors defamed The Wellness Group and Mr Murjani.
Osim said the allegations are "unmeritorious and groundless" and added that it would "vigorously defend the claims".
The company also said it would keep shareholders informed, and would make further announcements when appropriate.
This is the latest development in an ongoing legal action which dates back to February, when Osim and other shareholders were served a writ of summons by The Wellness Group and its chairman Mr Murjani over shares in TWG Tea.
Mr Murjani was a founder of the luxury tea and tea accessories firm launched in Singapore in 2007.
In a statement then, The Wellness Group claimed the other TWG Tea shareholders and directors had "conspired to injure the interests of The Wellness Group by diluting its shareholdings in TWG Tea and enabling Osim to take control".
Osim bought a 35 per cent stake in the company in April 2011, and gradually lifted that to 70 per cent by this January.
The lifestyle and wellbeing firm, together with other defending shareholders, issued a counterclaim for defamation against The Wellness Group and Mr Murjani in response to the first writ of summons.
It appointed Senior Counsel Davinder Singh of Drew & Napier LLC to represent it in February.