The Prime Minister has accused National of "politicking" by trying to make doctors tell parents if their daughter is having an abortion.
Helen Clark said yesterday she "strongly" opposed a law change being advocated by National MP and family spokeswoman Judith Collins.
She warned the health of girls might beendangered if the law compelled doctors to tell parents their child was pregnant and wanted an abortion.
Debate about an underage abortion provision in the Care of Children Bill is becoming intense amid fierce lobbying of MPs in the buildup to the next vote on the law, possibly next month.
Since 1977 the law has protected the privacy of girls under 16 who do not want parents told they are having an abortion.
That provision of the Guardianship Act is included in its replacement, the Care of Children Bill now before Parliament, providing an opportunity for MPs to debate it again.
Under Ms Collins' proposal, a girl would have to go to court to stop a doctor telling a parent or guardian that she wants an abortion.
Unusually, National is not allowing its MPs a conscience vote on the debate, saying it is about parental rights - not abortion. Labour is expected to give its MPs a free vote.
Doctors have spoken out against Ms Collins' proposals and yesterday warned it risked girls shunning doctors, which could lead to a rise in illegal, dangerous abortions.
They already have protocols in place where authorities can be alerted if a doctor suspects abuse.
Helen Clark said the present law had existed for 27 years without problems. She accused Ms Collins of being more interested in politics than the health of young girls.
Ms Collins said Helen Clarks' accusations were "seriously awful".
She said she was motivated not by politics, but by a need to protect girls who might have a secret abortion and be returned to a dangerous environment.
A decision on when the Bill will be debated in Parliament again is expected this week.
