Daiichi Sankyo and Ranbaxy Laboratories have issued a joint statement, to “allay market rumour and speculation”, confirming that the Japanese drugmaker's agreement to take over the Indian company was "binding and final”.

The rumours have been flying around all week that Daiichi Sankyo may pull out of the deal as details emerge of an investigation by the US Department of Justice into allegations that Ranbaxy falsified data on treatments. The Gurgaon-based firm has strongly denied claims that a number of its generic drugs that got onto the market in the USA without meeting the Food and Drug Administration’s standards.

Details of the investigation had sent Ranbaxy shares down over 20% in the first two days of the week but rebounded after chief executive Malvinder Singh said it would give the DoJ the documentation it requires to complete the probe.

The joint statement noted that "Daiichi Sankyo, Ranbaxy and the Singh family stand by the deal and confirm that the terms of the deal remain unchanged". It added that “all the synergies expected to accrue to the combine, remain intact as before”.