WHEN a baby was abandoned recently at a convent in central Poland, the incident highlighted a growing controversy. The Salesian order's "Okno Zycia" ("window of life") at Piotrkow Trybunalski is one of dozens of baby hatches to have opened in the past decade across Europe, offering people an opportunity to deposit their new-borns in secrecy.

An influential United Nations committee is now demanding the closure of all baby hatches, and debate is heating up over whether they should be allowed.

"We're not encouraging mothers to get rid of their babies," Agnieszka Homan, a spokeswoman for Caritas, a Polish church charity, says. "Although babies can be left legally in state hospitals, some are still being dumped outside in the cold. These 'Life Windows' enable women who don't want to give birth in hospital to leave them anonymously without endangering their lives."

HISTORIANS believe that Europe's first baby hatch, or "foundling wheel", was opened in Rome under Pope Innocent III in 1198. Most hatches, built into the doors of churches, were closed in the 19th century, as state social care expanded. But they began to reopen in the late 1990s, as more babies were abandoned amid economic hardship and social breakdown.

Most now consist of heated incubators with simple sign-directions, which trigger a bell when a baby is deposited inside. New-borns, usually left at night, are taken to hospital and withheld from adoption for several weeks, in case the parents reclaim them.

In Germany, the first modern Babywiege ("baby cradle") was opened in a wall of the Waldfriede Hospital in Berlin in 1999, on the initiative of a Protestant pastor, the Revd Gabriele Stangl. There are now about 80 in the country, and 15 in Austria.

Although child-abandonment remains illegal in Britain and other countries, a dozen of the 27 member-states of the European Union now allow baby hatches. Across the Continent as a whole, they are estimated to have received about 500 babies in a decade.

THIS number is small compared with those left soon after birth in hospitals in Europe. But supporters say that the hatches have public support. They reacted indignantly when the UN Committee for the Rights of the Child, which is based in Geneva, called for their closure last year.

In a UN Radio interview in June last year, a Hungarian member of the committee, Maria Herczog, denounced the hatches as "medieval", and a violation of the 1989 UN Convention on the Rights of the Child, Articles 7 and 8 of which enshrine a child's right "to know and be cared for by his or her parents", and "to preserve his or her identity".

There was no correlation between the prevalence of baby hatches and infanticide rates, Ms Herczog said, and "no evidence whatsoever" that lives had been saved. The hatches merely encouraged women to abandon their babies, and she would ask the European Parliament to vote for them to be scrapped, in favour of "proper child-protection services".

PRESSURE for closure of the hatches is growing. Several have already been suspended in Germany, whose federal constitution guarantees citizens a right to "know their origins".

In Poland, there have also been calls to close the 49 Life Windows now operating in the country, which have taken in 54 babies since the first one opened at Krakow in 2006. Magdalena Sroda, Professor of Ethics and Philosophy at Warsaw University argues that the hatches are a "Dickensian relic".

"Perhaps their closure would force the government to do something about providing sex education, recognising women's reproductive rights, and establishing the rights of children - not just to life, but to a worthy existence," Ms Sroda told the mass-circulation daily Gazeta Wyborcza recently.

"It's the prevailing view that a woman who doesn't want her child is a monster, a freak of nature, a personification of evil. So it's hardly surprising some women would rather kill their child than face such rejection."

Some social-work professionals in Poland believe that babies have been left by pimps or male relatives, without the mother's consent. They say that most have also been well fed and clothed, thus putting in doubt claims that they would otherwise be dumped on rubbish heaps. They also argue that the lack of information about the child's family background or potential health problems can cause difficulties.

Ms Homan, of Caritas, believes that the objections reflect misunderstandings. While the UN Convention's Articles 7 and 8 establish a child's right to know his or her origins, she looks to Article 6, which enshrines a child's "inherent right to life", and this has to take priority, she believes.

No one wants babies to be left in the Life Windows, she says; and when hatch in Krakow was opened, the archdiocese circulated 100,000 leaflets advising mothers that they would be better off abandoning their newborns in hospital.

Yet Ms Homan is adamant that the windows are essential as a final resort. Justice and police officials support them; and several city councils have adopted resolutions urging the Polish government to ensure that they stay open. Polish bishops, for their part, are counting on the Vatican, which is represented at the UN, to resist any attempt to close them.

The UN committee has not yet set a deadline; nor is there a date for a debate in the European Parliament; so supporters and opponents of the baby hatches will be lobbying hard in the months ahead.

Jonathan Luxmoore is a journalist who reports from Warsaw and Oxford.