Japanese drug maker Daiichi Sankyo was aware of the U. S.  Food & Drug Administration's (FDA's) probe into Ranbaxy's manufacturing practices and had therefore put in a clause in the acquisition deal that any liability emerging out of the probe would have to be borne by promoters Malvinder Singh & family.

Last month, Ranbaxy pleaded guilty to charges of manufacturing and distributing poor quality drugs and agreed to settle the charges by paying a fine of $500 million.

As Ranbaxy is now owned by Daiichi, the hefty fine will be paid by it.  But, a source aware of the agreement between the two companies said there was a clause in the agreement that could force Ranbaxy's previous owners to compensate Daiichi for the fine.

Japan-based Daiichi acquired promoters' stake in the Indian drug maker in June 2008.

Speaking on the topic, the source said, "The deal. had a clause that if the investigations led to any damages, it would have to be borne by the promoters as it related to the period before the Daiichi management took over."

However, sources close to Malvinder Singh & family declined any such clause in the agreement signed by the two companies.  Moreover, sources also say that Malvinder Singh & family can contest on the grounds that the Japanese drug maker should have challenged the claims rather than pleading guilty.