The Guardian reports: Rupert Murdoch’s global media empire is facing a challenge on a new front in the billowing phone-hacking scandal after a powerful US Senate committee opened direct contact with British investigators in an attempt to find out whether News Corporation has broken American laws.

Jay Rockefeller, chairman of the Senate committee on commerce, science and transportation, has written to Lord Justice Leveson, who leads the British judicial inquiry into media ethics, asking if he has uncovered any evidence relating questionable practices in the US.

“I would like to know whether any of the evidence you are reviewing suggests that these unethical and sometimes illegal business practices occurred in the United States or involved US citizens,” Rockefeller writes in a letter released on Wednesday.

The development adds to the potential dangers facing News Corp, a publicly-traded company with its headquarters in New York. Rockefeller has taken a close interest in the unfolding phone-hacking saga, but it is the first time that a Senate committee member has acted in his official capacity.