Ashok Kalyanjee, 46, slit the throats of sons Paul, 6, and Jay, 2, in his car at a beauty spot in the Campsie Fells, and then tried to torch the vehicle with himself and his victims inside.

Sentencing Kalyanjee at the High Court in Paisley, Lord Brailsford told him, "This is as grave a crime as can be imagined. This crime was premeditated, planned, organised.

"You used deceit and lies to persuade the children's mother and the children to go out with you that afternoon. You purchased the murder weapon in advance and acquired petrol.

Kalyanjee pleaded guilty to the charge, was reportedly consumed with hate for Giselle Ross, his Scottish ex-wife, and for Scotland. Born in India, he has been in the UK since 1991.

He married Ross in 2001 and the couple divorced in 2004.

"The victims were defenceless. No doubt they loved you and assumed you would take care of them as a father should. One of the victims witnessed what happened to his brother," Lord Brailsford said.

"I cannot imagine the suffering he must have endured. There is no mitigation for a crime of this enormity."

Kalyanjee showed no emotion as the sentence was pronounced, but his ex-wife Giselle Ross yelled at him in the court, "They were my babies. They never even loved you anyway".

Kalyanjee killed Paul and Jay on May 3 last year at a car park in the Campsie Fells near Lennoxtown, north of Glasgow. His sons did not want to spend the day with him but he lured them into his silver Mercedes with promises of toys.

Kalyanjee reportedly then bought a large kitchen knife and stashed petrol in the car boot. He phoned his ex-wife before the murders and said in a "cold, strange" voice, "Your babies are fine. Your babies are fine."

Then, before hanging up, he added, "You'll regret what you did to me in this life."

As he sat with Paul and Jay at the murder scene, Kalyanjee used a tape machine to record a chilling last message in Punjabi, "These children are mine and they go with me. This death is near."

Kalyanjee killed Jay before Paul, then poured petrol over the inside of the car and set it alight. The fire did not destroy the car. Kalyanjee collapsed in the front seat and spent six weeks in intensive care with burns.

His lawyer, Paul McBride, said Kalyanjee loved his sons and found it "difficult to understand" what he had done. He said Kalyanjee wrote a 345-page diary before the murders complaining about how he and his family had been treated in Scotland.