A Virginia lawmaker has apologised for being co-patron to a radical late-term abortion bill she says she never would have backed if she had read it properly.

Delegate Dawn Adams, a nurse practitioner, wrote to supporters in an email to say that adding her name to Kathy Tran's bill had been a 'mistake' and that its provisions 'sought to do much more' than what she had originally believed. 

The bill put forward by Tran in the Virginia legislature this week has caused outrage among Republicans and pro-life advocates. 

Asked if her bill would allow abortion up to the point of birth and even where a pregnant woman was 'dilating', Tran replied: 'My bill would allow that, yes.'

Apologising for her support, Adams wrote in her newsletter: 'I made a mistake, and all I know to do is to admit it, tell the truth, and let the chips fall where they may.

'If you follow my newsletter or have written to me to ask about my votes, you know that I do my best to read and research every bill I vote on. But I did not read a bill I agreed to co-patron and that wasn't smart or typical. I will work harder and be better for it.

'By now you have heard about the abortion bill, or seen the video. I vaguely remember signing on to this, and I did this in solidarity with my colleague and as a symbolic gesture for a woman's right to choose.'

She added: 'I am sorry that I did not exercise due diligence before this explosion of attention; had I done so, I would not have co-patroned.' 

In addition to allowing abortion up to the point of birth, Tran's bill 'eliminates the requirement that two other physicians certify that a third trimester abortion is necessary to prevent the woman's death or impairment of her mental or physical health' and removes 'the need to find that any such impairment to the woman's health would be substantial and irremediable'.

The furore over her bill escalated on Wednesday when Virginia Governor Ralph Northam addressed late-term abortion in an interview with the radio station WTOP-FM. 

'[Third trimester abortions are] done in cases where there may be severe deformities. There may be a fetus that's nonviable. So in this particular example, if a mother is in labor, I can tell you exactly what would happen,' he said.

'The infant would be delivered. The infant would be kept comfortable. The infant would be resuscitated, if that's what the mother and the family desired, and then a discussion would ensue between the physicians and the mother.'

Bishop Michael Burbidge of the Diocese of Arlington said that although the bill had failed, he was 'distraught' it had even been introduced. 

In a statement, he added that the governor's comments were 'staggering'. 

'[The bill] could have paved the way for babies to suffer a violent and gruesome death moments before birth and could have been harmful to women,' he said, adding that the views embodied in the bill and the governor's comments reflect 'a new level of deep-rooted animus against the inherent goodness of every child'. 

'Abortion of a baby in the final stage of pregnancy borders on infanticide,' he said. 

Northam has stood by his comments, saying: 'I have devoted my life to caring for children and any insinuation otherwise is shameful and disgusting.'