MANILA: Church leaders in the Philippines said Saturday that an impending birth control law aimed at reducing poverty in the conservative nation was one step towards legalising abortion.

In a letter penned by bishops to be read at Sunday mass in churches across the mainly Catholic country, they said the Reproductive Health Bill promoted pre-martial sex and threatened the "moral fibre" of the country.

"The Reproductive Health bill, if passed into law in its present form, will put the moral fibre of our nation at risk.... a contraceptive mentality is the mother of an abortion mentality," they wrote in the pastoral letter, which was posted on the website of the Catholic Bishops' Conference of the Philippines.

The bill paves the way for sex education in schools and the provision of free contraceptives in a country with one of Asia's fastest-growing populations.

It was passed by the lower house of parliament on Thursday and the Senate is expected to vote on it before Christmas.

The bill will be signed into law by President Benigno Aquino if both houses of parliament agree on a common version.

In addition, the bishops allege, to being a precursor to allowing abortion, the bill encourages pre-marital sex by giving young unmarried couples contraceptives to help them avoid pregnancy.

"Is this moral? Those who corrupt the minds of children will invoke divine wrath on themselves," said the letter.

Proponents of the bill deny that it promotes abortion, which is expressly banned by the Philippine constitution.

The Aquino government hopes the law will help bring down poverty in a nation of nearly 100 million people, as well as reducing the high maternal mortality rate.

The pastoral letter, however, rubbished the notion.

"It will not be so. The poor can rise from their misery through more accessible education, better hospitals and lesser government corruption," it said.

"Money for contraceptives can be better used for education and authentic health care."