The pro-choice group needs to collect 16,728 signatures

The South Dakota Campaign for Healthy Families aims to collect 16,728 signatures needed to put the ban on hold and put it to a public vote.

The law bans all abortions except to save a woman's life, but not in cases of rape or incest.

Its supporters hope it could help challenge the 1973 US Supreme Court decision that legalised abortions.

Many believe two recent conservative appointments to the Supreme Court may have tipped the balance in favour of anti-abortionists.

The supporters of the South Dakota law say they want to trigger a battle over the 1973 Roe-versus-Wade ruling, in which the US Supreme Court established that governments lacked the power to prohibit abortions.

June deadline

The South Dakota Campaign for Healthy Families filed papers with the state to start its petition drive.

Gov Rounds has said he expects the law to be challenged in court

If it obtains the necessary signatures by 19 June, the law will be put on hold until the voters decide on its fate in a question added to ballot papers in a November election.

If the petition fails, the law will take effect on 1 July.

About 800 abortions are performed each year in South Dakota.

Under the law signed by South Dakota Governor Mike Rounds earlier in March, doctors could get up to five years in prison and a $5,000 (£2,800) fine for performing an illegal abortion.

It is likely that a federal judge would suspend the ban if it was challenged in court.

The law would therefore not take effect unless South Dakota state got the case to the US Supreme Court and won.

Gov Rounds has said abortion opponents have already started offering money to help the state pay legal bills for the anticipated court challenge.