The House of Represenatives is girding itself for another wrenching debate on abortion after a House panel on Wednesday approved legislation that would ban almost all abortions after 20 weeks of pregnancy.

The vote came after the bill's sponsor, Arizona Republican Trent Franks, generated another controversy during the committee debate when, in response to a Democratic amendment making an exception to the abortion ban in cases of rape and incest, he stated that incidences of rape resulting in pregnancy "are very low".

Democrats were quick to call the claim "astonishing" and compared the remarks to the claim by former congressman Todd Akin's that the female body was capable of stopping pregnancies in the case of "legitimate rape".

Several recent court decisions have struck down similar state laws, and the GOP-backed bill has little future in the Democratic-led Senate, but the measure will give House conservatives a rare chance to reaffirm their social issue credentials.

The bill, named the "Pain-Capable Unborn Child Protection Act," was approved by the House judiciary committee on a party-line 20-12 vote and could get a vote in the full House as early as next week.

House Republican leaders, concentrating on budgetary and jobs bills and investigating administration scandals, have largely avoided contentious social issues such as abortion, but anti-abortion conservatives have been spurred by the recent conviction of a Philadelphia abortion provider, Dr Kermit Gosnell, for killing three babies born alive at his clinic.

"The terrifying facts uncovered during the course of the trial ... and successive reports of similar atrocities committed across the country, remind us how an atmosphere of insensitivity can lead to horrific brutality," said the committee chairman, Bob Goodlatte.

Franks and others argued that there is evidence – a contention Democrats say is unproven – that foetuses can feel pain after five months, justifying a ban on later abortions.

Representative Zoe Lofgren said Franks's statement on rape was "astonishing", and Democrats quickly compared it to the statement of Todd Akin, whose campaign for a Senate seat in Missouri collapsed last year after he stated that the female body was capable of stopping pregnancies in the case of "legitimate rape".

Franks later said that what he intended to say was that later-term abortions, such as those banned under his bill, were rarely the result of rapes.

A federal court in May overturned a 20-week abortion ban in Arizona, saying that the law violated a woman's right to terminate a pregnancy before a foetus is viable. Viability is generally considered to start at 24 weeks.

Some nine other states have enacted similar bans and have faced court challenges.

The National Right to Life Committee said the other state laws and the Franks bill were based on an NRLC model drawing on evidence that the unborn have the capacity to experience pain. It noted that the 20-week post-fertilisation age used in these measures is equivalent to 22 weeks of pregnancy under a widely employed dating system.

The leaders of the House Pro-Choice Caucus, Louise Slaughter and Diana DeGette, both Democrats, said that at a time when voters wanted Congress to concentrate on jobs and the economy, "the House majority has instead once again decided to reignite its war on women".

Democrats pointed out that all 22 Republicans on the judiciary committee were men.

The bill does provide for an exception to save a pregnant woman whose life is endangered by a physical illness arising from the pregnancy, but Republicans rejected Democratic amendments to expand those exceptions to include rape, incest or non-pregnancy-related illnesses.