The Labour leadership contender Diane Abbott yesterday said the coalition government's budget would "bear most heavily" on women and the poor.

Abbott used a Commons debate to accuse the chancellor, George Osborne, of delivering an "unfair and aggressive" budget that would hit women through its package of welfare and public spending cuts.

The equalities minister, Lynne Featherstone, insisted the government's tax and spending plans were fair and included protection for the most vulnerable in society.

Abbott, the MP for Hackney North and Stoke Newington, said: "This is a budget, these are a package of public expenditure cuts, which will bear most heavily on the poorest, bear most heavily on women.

"George Osborne, our chancellor, has cut and frozen too many programmes which were aimed largely at women in one of the most unfair and regressive budgets that I have seen in 23 years in parliament.

"His decisions to freeze child benefit, scrap the child trust fund, stop Sure Start maternity grants, abolish the health in pregnancy grant, cap housing benefit and freeze public pay will all have a greater impact on women than men."

House of Commons library research had shown women would shoulder "the biggest burden of the cuts".

Abbott said that, of the £8bn to be raised from cuts and taxes, £5.8bn would come from women.

Featherstone sparked protests from Abbott and her colleagues on the Labour benches by criticising the impartial and respected House of Commons library.

She said: "I would say that the library findings were biased in their budget analysis – it was not robust ... it only included selected measures."

Abbott questioned whether it was in order to "impugn the professionalism and integrity" of the library staff.

Featherstone said: "No integrity was being impugned, but the Commons library research paper itself notes that it is not a detailed assessment based on individual tax and benefit data and therefore remains a rough and ready approximation."

She added: "We are absolutely committed to a fairer future for women and their families."