A former Sunday school teacher's attempt to overturn her conviction for murdering the wife of her ex-lover has failed.

The Court of Appeal in Belfast refused Hazel Stewart's appeal against her conviction for the murder of Lesley Howell in Co Derry in May 1991.

Lord Justice Malachy Higgins said: "There is no reason to doubt the safety of this conviction."

Stewart, 49, this morning dropped her appeal against conviction for the murder of her husband Trevor Buchanan more than 20 years ago.

Stewart was jailed in 2011 for planning the killings with her former lover Colin Howell. She is serving a minimum of 18 years in a prison in Belfast.

Mr Buchanan, 32, and Mrs Howell, 31, were found dead in a fume-filled garage in Castlerock, Co Derry, surrounded by family photographs.

Police originally believed it was a suicide pact after they realised their partners were having an affair.

But they were murdered with car exhaust fumes piped into their rooms as they slept.

Their bodies were arranged by Howell in the car to make it appear they had taken their own lives.

It took nearly two decades for the truth to emerge when Howell, 52, dramatically confessed to both killings, pleading guilty in 2010. He is serving a minimum of 21 years in prison.

Howell implicated Stewart in the plot and gave evidence against her during her trial.

In March 2011, a jury at Coleraine Crown Court found Stewart guilty on two counts of murder.

The prosecution said she knew about the plan in advance and actively facilitated her husband's killing by ensuring he was drugged and allowing Howell into her home.

She also disposed of evidence, including the hose pipe used to gas their spouses.