A former CEO of French-Swiss cement maker LafargeHolcim said he was made aware of payments to the Islamic State group in August 2014, contradicting an account by another top executive, a source close to the case said Saturday.

Lafarge is accused of paying the terrorist group and other militants $12.9 million between 2011 and 2015 so that the company's factory in Jalabiya, northern Syria, could continue to operate despite the war.

According to a report commissioned by LafargeHolcim and seen by AFP, Lafarge's Syrian subsidiary Lafarge Cement Syria (LCS) paid out some $5.6 million (4.7 million euros) between July 2012 and September 2014.

Of this, more than half a million dollars went to IS, according to an April report by US consultants Baker McKenzie.