The inquest into Amy Winehouse's death may be declared invalid after it was revealed the coroner in charge did not have the correct qualifications for the role.

In October, Suzanne Greenaway recorded a verdict of death by misadventure, stating the singer died as an "unintended consequence" of drinking too much alcohol.

It has now emerged that Greenaway resigned from her job just a month after completing the investigation into Winehouse's death because she did not meet the strict guidelines over the appointment of coroners.

According to the rules, Greenaway should have been a solicitor in the Law Society for at least five years, but she had only been part of the organisation for two-and-a-half.

She should also have served five years as a "qualified medical practitioner", but the Australian only qualified as a nurse in her native country.

It could mean that all 30 of the inquests she worked on, including Winehouse's, could be declared illegal - but officials insist this will only happen if the verdicts she recorded are challenged in the High Court, reports Britain's The Sun.

Greenaway's husband, Inner North London Coroner Dr Andrew Scott Reid, who appointed her to the role, tells the publication, "In November it became apparent I'd made an error in the appointment process. While I am confident that all of the inquests handled were done so correctly, I apologise if this matter causes distress."