Media mogul Rupert Murdoch and his son James have caved into pressure to attend a British Government culture, media and sport Government committee hearing next week as the phone hacking scandal rumbles on.
Earlier in the day, News International chief executive Rebekah Brooks agreed to attend the hearing.
In the US, Murdoch senior is also is facing growing calls for an inquiry in the US after senators questioned whether News Corporation had engaged in "criminal" activity in America, including the possibility that the relatives of 9/11 victims had their phones hacked.
Peter King, the first Republican to call for the claims to be investigated, said the FBI should be brought in.
Mr King, chairman of the House Homeland Security Committee, made the request in an open letter to Robert Mueller, the FBI director.
"Any person found guilty of this purported conduct should receive the harshest sanctions available under law," he said.
Senator Jay Rockefeller, chairman of the commerce, science and transportation committee, said that in the event of an investigation his "bet" was that "we'll find some criminal stuff". "This will be a huge issue," he said, adding that his own committee may open an inquiry.
"I am concerned that the admitted phone hacking in London by News Corp may have extended to 9/11 victims or other Americans. If they did, the consequences will be severe," added Mr Rockefeller, a Democrat from West Virginia.
Sen Rockefeller wrote a letter with Sen Barbara Boxer of California, the chairman of the select committee on ethics, urging Eric Holder, the attorney general, and Mary Schapiro, chairman of the Securities and Exchange Commission, to investigate News Corp, Mr Murdoch's umbrella company.
"The reported allegations against News Corporation are very serious, indicate a pattern of illegal activity, and involve thousands of potential victims. It is important to ensure that no United States laws were broken and no United States citizens were victimised," they said.
Senator Robert Menendez of New Jersey, also wrote to Mr Holder, asking him to examine whether journalists working for Mr Murdoch tapped into the phones of the victims of the September 11 terrorist attacks. Families of the victims last night reacted angrily to reports that the News of the World tried to buy phone records of their loved ones from a former New York police officer.
"Someone should look into it to see if their rights were violated – the family members I've talked to are appalled," said Jim Riches, a former deputy fire chief in New York whose 29–year–old son, also a fireman, died in the attacks.
"I think they crossed the line. It's horrible, and they should be held accountable," he told Politico, a US website.
Members of the family that controlled the Wall Street Journal said they would not have agreed to sell the newspaper to Mr Murdoch if they had been aware of News International's conduct in the phone-hacking scandal at the time.
"If I had known what I know now, I would have pushed harder against" the Murdoch bid, said Christopher Bancroft, a member of the family that controlled Dow Jones & Company, publishers of the Wall Street Journal.
The chief executive of News Ltd, Mr Murdoch's Australian newspaper group, announced that it was opening a review of all editorial expenses from the past three years to ensure they were for "legitimate services".
In the US, senators expressed concern that members of staff at Murdoch publications could have transgressed the Foreign Corrupt Practices Act, which makes it illegal for employees of any US company or its subsidiary to bribe foreign officials.
The majority of Murdoch's empire is made up of his US assets, which include Fox News, the Wall Street Journal, the New York Post and 20th Century Fox film studio.