US-headquartered pharmaceutical major Merck has been subpoenaed by the US Department of Justice, owing to a criminal investigation surrounding marketing practices for three prescription medicines.

The Department of Justice issued the subpoena requesting information regarding marketing and selling activities relating to the company’s Temodar, PegIntron and Intron A medications.

The latest case follows a string of investigations into Merck’s practices, with the company also under investigation for marketing of its now defunct arthritis medication Vioxx, while also being subject to a probe into the company’s activities overseas as part of the US Foreign Corrupt Practices Act.

Merck confirmed it is cooperating fully with the latest investigation, while the company has also set aside a $950m reserve fund to cover liabilities resulting from the Vioxx case.