Malvinder Singh's Ranbaxy Labs is already facing legal action from the US pharma regulator, FDA for allegedly selling adulterated products. Now, a US Congress panel wants to probe if the regulator was slack in approving Ranbaxy's drug approvals. US media reports also suggest the House Energy and Commerce Committee would also look at why the FDA continued to approve medicines made by the company and allow shipments into the US when it was already investigating Ranbaxy's manufacturing processes.