FORENSIC scientist Dr David Schudel, who specialises in fire investigation, told a jury at Newport Crown Court that a naked flame was the "most likely" cause of the fire, which ripped through the Cwmbran home.

The specialist was giving evidence at the trial of Carl Mills, 28, who is charged with the murder of Kayleigh Buckley, 17, her mother Kim Buckley, 46, and six-month-old daughter Kimberley on September 18, 2012.

Mills denies the charges.

He said the blaze was most likely started by the application of a naked flame to materials in the porch of the house but said he could not rule out it was not caused by a discarded cigarette.

The court heard he “broadly agreed” with conclusions made by forensic scientist Emma Wilson, who gave evidence earlier in the trial, and said he believed the blaze was likely caused by a lighter or a match.

He said he looked at research into fires caused by both manufactured and roll-up cigarettes and said he couldn’t rule out that the Tillsland fire was not started this way.

He said the latest statistics available, showed there were 37,601 accidental fires in the UK 2011/12 with 2,673 found to have been caused by cigarettes. Of those fires, 244 involved fatalities the jury heard.

Dr Schudel said tests had been done with cigarettes and waste paper bins and in some circumstances the smouldering fire took hold into a much larger one.

He said manufactured cigarettes now contained invisible barriers inside so that if left lit but not smoked for a period of time they would self extinguish.

But he said he had done tests, which proved these barriers did not always work and the cigarettes continued to burn.

He said high profile fires in Bradford City stadium and at London’s Kings Cross Station were thought to have been started by cigarettes.

He added that although roll up cigarettes were more likely to self extinguish when lit, they could still cause a fire in the right conditions.