US billionaire Donald Trump has bitterly attacked Lord Sugar as “never successful” enough.
Mr Trump fronts the American version of the tv show The Apprentice.
In a Twitter attack on the BBC star, Mr Trump told the self-made Londoner: “Unlike you, I own The Apprentice. You were never successful enough.”
The spat, over the last 24 hours, was ignited by Lord Sugar’s support of the UK government subsidising Scottish windmills.
“If you think ugly windmills are good for Scotland you are an even worse businessman than I thought,” said the American businessman.
He went on : “Keep working hard so I make plenty of [dollars] with your show.
“Look in the mirror and thank the real Lord that Donald Trump exists. You are nothing!”
Lord Sugar, an ardent supporter of Jewish Care, was recently embroiled in a Twitter row with X Factor judge Tulisa Contosavlos.
He told music tycoon Simon Cowell, whose father is Jewish, to “get back here and do X Factor yourself and chuck Tulisa out.
“She knows nothing and talks rubbish.”