Metropolitan Police commissioner Sir Paul Stephenson has resigned following the phone hacking scandal.
Britain's most senior police officer has faced criticism for hiring former News of the World executive Neil Wallis as an adviser.
In standing down on Sunday, Sir Paul said he had no knowledge of the extent of the phone hacking.
Prime minister David Cameron said he respected and understood Sir Paul's decision and home secretary Theresa May said she was "sorry" he had resigned, thanking him for all the work he had done during his time in office.
May said she would address MPs today over her "concerns" over the closeness of the relationship between News International and police.
Ed Miliband has called for the Commons to sit on Wednesday to ensure that the prime minister answers the many unanswered questions that he faces.
He said: "Rebekah Brooks has been arrested, the Metropolitan Police Commissioner has resigned, tomorrow we will have some of the most important Select Committee hearings in modern times and the Prime Minister has decided to leave the country, not to return until after Parliament breaks up for summer.
"In these circumstances the right and responsible thing for the government to do must be to extend the parliamentary session for at least 24 hours so the House of Commons meets on Wednesday.
"It would give MPs have the chance to debate the issues arising from the select committee hearings and ensure the Prime Minister answers the many unanswered questions that he faces.
"Unless the government agrees to Parliament meeting on Wednesday, MPs cannot do their jobs properly and the prime minister has no chance of sorting out this crisis."
Speaking this morning, the Labour leader will blame the phone hacking scandal on a culture of "irresponsibility" that also led to the banking crisis and MPs' abuse of their expenses.
In a speech at KPMG in central London, Miliband will say that all three episodes were caused by some of the most powerful people in society thinking they were "untouchable" and could act as they pleased.
He will also call for a change to the media ownership laws, saying that the size of Rupert Murdoch's empire is "not healthy".