The Press Complaints Commission received 384 complaints over the Daily Mail’s coverage of Ed Miliband’s father.
Most of the complaints have been in connection with Clause 1 of the Editor’s Code dealing with accuracy.
Miliband himself has not lodged a complaint with the PCC and a source close to the Labour leader said he was more interested in promoting debate on the issue rather than securing an adjudication.
A PCC insider told Press Gazette: "At 4pm today we counted 384 complaints about the coverage. In exceptional circumstances we can initiate an investigation based on a third party complaint but when there is somebody clearly identifiable we like to talk to them first."
The Daily Mail ran a double-page critique of the Labour leader's late father on Saturday under the headline 'The man who hated Britain'.
The Mail's assessment of Ralph Miliband was based largely on comments he wrote as a 17-year-old during the Second World War: "the Englishman is a rabid nationalist" and "you sometimes want them almost to lose (the war) to show them how things are".
Aged 45, Miliband senior wrote of his disdain for the British establishment, saying it included: "Eton and Harrow, Oxford and Cambridge, the great Clubs, the Times, the Church, the Army, the respectable Sunday papers … the House of Lords … social hierarchies, God save the Queen."
The Mail gave Ed Miliband right of reply yesterday in which he defended his father. Miliband has described the Mail's story of Saturday as a "lie".
The Mail said in a leader column today: "Nothing is more natural than a child’s love for its parents.
"Indeed, Ed Miliband struck a chord with many readers by springing to his father’s defence after the Mail’s exposé of the latter’s political philosophy – a philosophy that underpinned incalculable human misery.
"But while it is certainly astute PR for the Labour leader to present his complaint against the Daily Mail in purely personal and emotional terms, it is also a mite disingenuous.
"For as he is aware, this is not just a personal issue. It is a fundamental question of ideology and enormous public interest."
Clause 1 of the Editors' Code, which underpins the PCC, says: "The press must take care not to publish inaccurate, misleading or distorted information, including pictures."
It also states: "The press, whilst free to be partisan, must distinguish clearly between comment, conjecture and fact."
Miliband has not made a complaint to the PCC personally. A source close to the Labour leader explained: "This is about right and wrong, not regulation." The source added they wanted to encourage public debate instead of securing a PCC judgement on the issue.