These are tempestuous times for Bibiana Aido, the Spanish minister of equality, who is known to friends and admirers simply as “Bibi”.

At 32, she is the youngest member of the cabinet and, as pioneer of a law making abortion readily available to teenagers, has become a hate figure for conservatives who have staged protests outside her family home near Cadiz.

An anti-abortion group known as Bebe Aido — a play on her nickname and the Spanish word for baby — has been circulating plastic foetuses to mobilise opposition to the reform that would give 16-year-olds the right to abortion without parental consent. The group claims to have the support of Queen Sofia, although protocol forbids her from public comment.

Aido, a radical feminist, has fuelled outrage by suggesting that abortion was no bigger an issue than breast enlargement. A foetus, she said, was “a living thing, clearly, but we cannot talk of a human being because this has no basis scientifically”.

Encouraged by 500,000 Spaniards who took to the streets of Madrid last weekend in protest, the country’s bishops have called on the government to back down and have threatened MPs backing the new law with excommunication.

Their muscular stance seems to have the backing of the Vatican: a new papal nuncio has been dispatched from Rome to replace a moderate figure accused of being too close to Jose Luis Rodriguez Zapatero, the Socialist prime minister. He was photographed sharing a bowl of soup with the leader.

Zapatero, who has described himself as a “feminist”, shows no sign of retreat. Under his administration, Spain has legalised gay marriage, introduced fast-track divorce and toughened penalties against wife-beaters. The bill would declare abortion to be a woman’s right. Debate is scheduled to begin in parliament next month.

Both sides are angry. Pilar Bardem, mother of Javier Bardem, Spain’s best-known actor, was seen arguing with anti-abortion campaigners who threatened to disrupt what they called a “death party” aboard a Dutch ship that docked in Valencia offering free abortions in international waters.

Under Spanish law, abortions are allowed only if pregnancy puts the mother’s physical or mental health at risk or in cases of rape or if there is foetal malformation. The most controversial aspect of the new law is its confidentiality clause for teenagers.

Leaders of the opposition Popular party have asked why a girl who cannot legally buy a drink should be allowed to have an abortion without her parents’ knowledge. “The inconsistency is crushing,” wrote Sandra Moneo, a conservative MP. “No father or mother can understand the idea of a minor going through the trauma of abortion without the advice, support and opinion of her parents.” Socialists were outraged when Antonio Canizares, a Spanish cardinal who holds a key position at the Vatican, suggested that abortion was worse than sexual abuse of children.

Zapatero, 49, was asked how he would feel if his daughter, after she turned 16, had an abortion without telling him. He said that he would prefer that she tell him and that it was up to parents to instil that kind of trust in their children. “But in the end, the decision is up to the person deciding whether to voluntarily interrupt a pregnancy,” he said.

Carmen Monton, a Socialist MP, said the proposed law was designed to help girls from troubled families who need an abortion and cannot tell their families. “We are not legislating for model families with fantastic relations between parents and children,” she said. “We are legislating for all of society.”

Even some in Zapatero’s camp are opposed to the move. Jose Bono, a leading Socialist figure and devout Catholic, has been seen locked in heated, private debate with Aido in the corridors of parliament.

According to one recent survey, 71% of Spaniards oppose abortion reform but Zapatero, who has also championed legislation to crack down on conjugal violence and rape, seems determined.

Josefina Elias, a pollster, said Zapatero’s mistake was to have avoided a more organised, public debate. She claimed that the law had been presented with all the delicacy of “an elephant charging into a china shop”. One of Zapatero’s former lieutenants put it even more bluntly: “That boy has no idea,” he said.

Times Recommends

• Should Knox’s trial even have reached the courtroom?
• 'Was it real?' The US bailout nightmare
• Iranian opposition plays the long game