Abortion clinics across England are undergoing unannounced inspections after concerns that consent forms were being pre-signed - before a woman had even been seen.
Health Secretary Andrew Lansley has ordered the Care Quality Commission checks to see if clinics are abiding by the law.
Around 250 clinics have been visited and there are concerns that 20 per cent were "non-compliant" with the law or regulations.
But critics have accused the Government of making a politically motivated attack on abortion clinics and questioned the need for the checks.
Ann Furedi, chief executive of the British Pregnancy Advisory Service, said: "As far as I am aware there is nothing different about the way that doctors are practising now than the way that they were practising five years ago or 10 years ago."
The law says two doctors must certify an abortion, except in emergencies. However, there is no requirement for them to have actually seen the woman - only that they should have seen and assessed the necessary clinical information about her case, which could have been taken by another doctor or nurse.
The concerns raised by the health secretary are that doctors are signing forms before any clinical assessment has taken place, which would mean they would not know the circumstances of the woman involved.
Mr Lansley told the BBC: "I am shocked and appalled to learn that some clinics - which look after women in what are often difficult circumstances - may be allowing doctors to pre-sign abortion certificates. This is contrary to the spirit and the letter of the Abortion Act.
The process of pre-signing certificates where the doctor does not know who the woman is for whom that certificate may be used in relation to that abortion is in itself illegal. I am not prepared to tolerate a failure to respect the law.