Drugmaker Merck has set up an independent committee to review the firm's actions prior to the withdrawal of its painkiller Vioxx from the market in September.

The arthritis treatment was taken off the market after studies showed that long-term use increased the risk of heart attacks and strokes. A report last month, citing internal Merck documents, suggested the company had tried to cover up risks for years.

Merck said in October that 1,000 groups had filed Vioxx-related lawsuits against the company.

Merck has appointed William Bowen, chair of the firm's corporate governance committee, to chair the special committee. He said: "Even though the food and drug administration has noted that the company acted responsibly with respect to Vioxx, the board concluded that its responsibilities to Merck shareholders made it important to conduct an independent review to ensure that the company acted in an appropriate and ethical way."