When US regulators raised concerns during their visit to a factory operated by Ranbaxy, the Indian generic drugs group, no one involved imagined that their inquiry would last so long, become so public or raise the stakes so high.

Since an inspection by the Food & Drug Administration (FDA) at the Paonta Sahib plant in February 2006, there has been a drawn-out battle for extra information, triggering raids and subpoenas last year from the Department of Justice.