A builder lured his wife's lover to an "ambush" at a remote farm and "executed" him in cold blood, a court heard.

Prosecutors allege Andrew Jones murdered Michael O'Leary because he had discovered he was having an affair with his wife.

Jones, 53, claims the .22 rifle accidentally went off while he and Mr O'Leary, 55, grappled during an argument at Cyncoed Farm in Carmarthenshire in January this year as he confronted him over the secret relationship.

Swansea Crown Court heard he disposed of the father-of-three's body by burning it in an oil drum at a yard adjacent to his home in Carmarthen.

Jones, who ran his own building firm, had learned months earlier his wife, Rhianon, 51, was having the fling with married Mr O'Leary - but she had insisted it was over.

William Hughes QC, prosecuting, told jurors during his closing speech there was only one reason Jones had taken a loaded rifle to the farm, and that was to kill Mr O'Leary.

"The prosecution say that he decided with clarity to make Mike O'Leary disappear and carefully planned his criminal act, ensuring he was the only person to have Rhianon," Mr Hughes said.

"This was no accident. When Mr O'Leary turned up at Cyncoed Farm expecting to meet Rhianon he was met by Mr Jones at an ambush site, in a cold, dark winter's night.

"Mr Jones had no intention of speaking to Mr O'Leary. That scenario of placing himself behind the Biffa bin does fit in with the other evidence.

"Either Mr Jones shot Mr O'Leary dead immediately or may have shot him initially to injure him and say some final words before shooting him dead.

"Michael O'Leary does end up on the ground defenceless and Mr Jones soon shoots him. Perhaps, you might think, one scintilla of truth in various accounts given to the police are the last words.

"Mr Jones says it is in the context of him going to tell Mike O'Leary's family about the relationship, 'Please don't do it, Jones'.

"Or are those the last words of a man about to be shot, pleading for his life?"

Mr Hughes suggested if Jones's intention had been to scare Mr O'Leary and warn him off, he could have taken one of his replica weapons instead.

He also suggested the defendant could have telephoned Mr O'Leary and told him to "sling his hook".

"That did not happen. Why did he not call him? Why not arrange to meet in an open space away from their families to have it out?," Mr Hughes asked.

"Given that Rhianon had said to him before it was over, and it had continued, how can Mr Jones ensure that she doesn't go back to Mike O'Leary?

"The answer, we say, is clear to Mr Jones. Get rid of Mike."

Mr Hughes said Jones had maintained that neither of them would be harmed.

"But taking a loaded firearm doesn't fit with not causing or anticipating any harm to anyone. In fact, it is quite the contrary," he said.

"It was taken with a view to ambush Mike O'Leary and to execute him, in effect. Have this in mind, throughout the accounts Mr Jones has given, it is only his version of what happened at the farm."

Jones, of Bronwydd Road, Carmarthen, denies murder. The trial continues.