Samaha was convicted of transporting explosives to carry out attacks and assassinations of political and religious figures in Lebanon with the help of Syrian security services.
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The ex-minister was arrested in 2012 and sentenced in May 2015 to four and a half years in prison, but that conviction was quashed a month later and a retrial ordered.
"The prosecution asked for the death penalty but he was sentenced to 13 years with hard labour," the judicial source said.
Under Lebanese law, the actual time Samaha has been sentenced to amounts to around 10 years.
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The former minister was also stripped of his right to vote or stand for public office, the source said.
Samaha, a Christian politician and former adviser to Syrian President Bashar al-Assad, admitted during his previous trial that he had transported the explosives from Syria for use in attacks in Lebanon.
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But he argued he should be acquitted because he was a victim of entrapment.
His previous sentence was denounced as "scandalous" by Justice Minister Ashraf Rifi as it would have seen him released at the end of 2015 because of time served.
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