The bickering, via interviews on competing radios and TV channels, came a day after a group of rebel Socialist lawmakers — including the former education, culture and environment ministers — abstained in a first parliament vote on France's 2015 budget, which nevertheless went through with a small majority.
The public spat is likely to further embarrass the deeply unpopular Hollande, who has been unable to stem increasingly strident dissent within his party despite two cabinet reshuffles and public remonstrations.
First in line to vent his anger was Jean-Christophe Cambadelis, Socialist party chief and a Hollande ally, who told RTL radio he was "shocked" by former education and culture ministers Benoit Hamon and Aurelie Filippetti abstaining on the vote.
Both were left out of the government in an emergency August reshuffle initiated by Hollande to flush out dissenters.
He said their abstention "posed an ethical problem" and slammed "an attitude which for me is appalling", pointing out that they had both approved part of the budget during a July cabinet meeting when they were still ministers.
Government spokesman Stephane Le Foll, meanwhile, said they had "neglected their duties", as had former environment and energy minister Delphine Batho, who also abstained.
Quick to react, Filippetti told i-TELE that she had "no lessons to receive from anyone," accusing Cambadelis of being "slightly dishonest".
Hamon went a step further, saying the government's current reformist, pro-business stance "threatens the republic" and would lead to a "huge democratic disaster" in the next presidential elections in 2017.
He warned on RFI radio that this disaster was "not only that (far-right leader) Marine Le Pen would get to the second round of elections without any resistance, but also the threat that soon, she will lead the country".
The rebel lawmakers – a hard-core rump on the left of the Socialist party – are unhappy with public spending cuts and tax breaks for companies initiated by the government to try and emerge from a deep economic crisis.
France has so far been unable to stem sky-high unemployment and kickstart growth. The eurozone's second-biggest economy has also admitted it will be unable to get its ballooning budget deficit below the EU ceiling until 2017 – two years later than promised.