The judicial screws are tightening on Rupert Murdoch's empire in America as the US justice department prepares to subpoena News Corporation in its investigation into whether the company broke anti-bribery and hacking laws on both sides of the Atlantic. The news that subpoenas are being drawn up, reported by News Corp's flagship newspaper the Wall Street Journal, comes a week after attorney general Eric Holder said he was launching a preliminary investigation into the media group as a result of the UK phone-hacking scandal. In addition, it has emerged that federal prosecutors have begun probing allegations that News Corp's advertising arm in the US hacked into a computer of a competitor as part of a campaign to crush its rival. News Corp also faces a possibly lengthy and costly federal probe into whether it broke anti-bribery laws as part of the illegal News of the World phone hacking in the UK. The company is potentially liable under the Foreign Corrupt Practices Act (FCPA), which bans US-based companies from profiting from bribery and corruption in other countries. News Corp is a US-based firm, its headquarters on Sixth Avenue in Manhattan. FCPA experts have suggested that it could be brought under the auspices of the act because News of the World journalists bribed police officers in the UK in search of exclusive stories that in turn increased sales and generated profits.