The prime minister rejected the charges, instead pointing to the abandonment of the mostly elderly victims.
"Obviously, I own up to my share of responsibility in this tragedy, but I reject any notion that the public authorities did not work properly," Prime Minister Jean-Pierre Raffarin told the Journal du Dimanche newspaper.
His defence of the handling of the crisis came after the deadly two-week heatwave broke, and followed an outcry from doctors and the opposition that the government underestimated the disaster and failed to act fast enough.
The persistent temperatures of around 40 degrees Celsius hit elderly people the hardest, particularly those who lived alone in apartments in Paris and other cities, according to authorities.
France's traditional month-long vacation period in August aggravated the situation, since many hospitals were understaffed and neighbourhood doctors were away.
By the time the government did act last Thursday - launching a national emergency plan, boosting hospital beds and staff, and setting up temporary morgues - the heatwave was receding.
The head of the opposition Socialist party, Francois Hollande, told the Journal du Dimanche that Raffarin's government was guilty of "a lack of anticipation - everybody knew the heatwave was going to last; a lack of vigilance - the public alerts weren't taken seriously; and a lack of response."
"It's the entire government that is on the spot for what I would call ... a serious leadership problem"
Opposition leader Francois Hollande
He added: "It's the entire government that is on the spot for what I would call ... a serious leadership problem."
Health Minister Jean-François Mattei confirmed on Sunday that the number of deaths was "estimated at between 1600 and 3000" and that the final figures, expected next week, would "probably be around the upper part of this range."
"This is a catastrophe, a human tragedy because thousands of lives were lost," he said later in the day during a visit to a Red Cross centre.
"And this human catastrophe struck the most fragile and lonely among us."
But the minister insisted that the situation, now that the heatwave had passed, "is totally under control, but the health alert remains in place".
Old and lonely
The state hospitals authority for Paris agreed with Mattei's assessment, saying admission levels were back to those seen before the heatwave although staff were "very tired" from the previous days.
Health minister Mattei has put alerts in place
Mattei vowed a "transparent" review of how the crisis was handled, but said he did not feel like a scapegoat despite the criticism heaped on him.
Raffarin continued to blame the isolation of the elderly within French society for the high number of deaths.
Visiting a retirement home to emphasise his point, Raffarin on Saturday blamed the crisis on the general neglect of senior citizens in France.
Noting that half of those who succumbed to the intense heat died at home rather than in hospitals, Raffarin said the "loneliness of old people is a deep fault in French society."