The commission said it had been "grossly undervalued" by the comments made today by both leaders.
This follows Wednesday's remarks by commission chairman Baroness Buscombe, who said "words could not describe" how angry she was at having been lied to by the News of the World over the phone hacking scandal.
Talking to Andrew Neill in an interview for the BBC Buscombe admitted the PCC had been misled by the News of the World.
The comments followed a series of allegations this week, including that the News of the World hacked into the phone of murdered teenager Milly Dowler while she was missing in 2002.
Speaking at Thomson Reuters today, Miliband called for "wholesale reform of our system of regulation", adding that the PCC "has failed".
"It failed to get to the bottom of the allegations about what happened at News International in 2009. Its chair admits she was lied to but could do nothing about it.
"The PCC was established to be a watchdog. But it has been exposed as a toothless poodle.
"Wherever blame lies for this, the PCC cannot restore trust in self-regulation. It is time to put the PCC out of its misery. We need a new watchdog."
He added that a form of self-regulation would be the best way forward but that any new body should have "far greater independence of its board members from those it regulates" as well as proper investigative powers and an ability to enforce corrections.
"Change should be led by the many decent editors and people in the industry who want to see change.
"I call on journalists, and those concerned with decent journalism, to put the reform of the system of self regulation at the centre of their concerns.
"To see in that a way of regaining and retaining the trust of those you need most: your readers. The inquiry is one place from which this reform can be made."
Also speaking on the matter today prime minister David Cameron similarly accused the PCC of having failed and lacking in public confidence.
He called for a replacement body to be "truly independent", adding that it would be "much better on a cross party basis"
But the PCC said in response to Miliband's comments that calls for the scrapping of the body were "wrong", referring to his remarks as being "long on rhetoric and short on substance".
"He appears to be ignorant of the important and valued work of the PCC," a statement said.
"However, he is right to support self-regulation and to say that the phone hacking scandal should act as a catalyst for improvement and reform of the industry.
"Indeed, his remarks simply echo the statement the PCC itself issued on Wednesday. We believe that the industry is fully committed to the Press Complaints Commission, and will respond appropriately to this challenge.
"Mr Milband offers three areas for particular change: greater independence of its board members from those it regulates; proper investigative powers; and an ability to enforce corrections.
"Mr Miliband is effectively agreeing with the PCC's own statement, which said that the areas of proposed reform should be: 'its own constitution and funding arrangements, the range of sanctions available to it, and its practical independence'.
"However, it is worth pointing out that the PCC exercises the power to enforce corrections on a daily basis. It dealt with thousands of complaints across the whole newspaper and magazine industry in 2010, many involving corrections and apologies.
"The PCC has to agree prominence of all corrections in advance. Mr Miliband, in this respect, is suggesting a change that already exists."
In a separate response to the prime minister's remarks the PCC added that it welcomed a fair and open, evidence-based inquiry and that this would recognise "the considerable successes" of the commission.
"We do not accept that the scandal of phone hacking should claim, as a convenient scalp, the Press Complaints Commission.
"The work of the PCC, and of a press allowed to have freedom of expression, has been grossly undervalued today.
"However, as the PCC has said consistently, it believes that the outcome of phone hacking should be a more independent PCC. It is confident that it is precisely what the Prime Minister's inquiry will also have to conclude."
Image by Peter MacDiarmid/PA