(Adds source on candidate for Leonardo appointment)
By Stefano Bernabei and Massimiliano Di Giorgio
ROME, March 16 (Reuters) - Italy is expected to replace the chief executives of Poste Italiane and Leonardo in a round of appointments at state-controlled firms this month, several sources close to the matter told Reuters on Thursday.
The Italian Treasury is expected to announce by March 20 who will run some of the country's biggest companies, including oil firm Eni and utility Enel.
Sources said it is set to give the CEOs of Eni, Enel and air traffic controller Enav new mandates but there could be changes at the top of Italian post office and defence and aerospace company Leonardo.
The Treasury and the companies involved declined to comment.
Veteran banker Alessandro Profumo, who stepped down as chairman of the troubled Monte dei Paschi di Siena in August 2015, is seen as a frontrunner to take the helm at defence group Leonardo, a source said.
Francesco Caio, a former McKinsey manager, was appointed as CEO of the post office in May 2014 to orchestrate the turnaround and privatisation of the company.
The listing of Poste Italiane was a key measure of former Prime Minister Matteo Renzi's agenda to reduce public debt and make state-owned companies more efficient.
While the government sold a 35 percent stake in October 2015, plans to sell another minority stake, initially due in autumn last year, appear to have been put on hold.
Sources also told Reuters that the government was unhappy that a consortium led by Poste Italiane pulled out of the race to buy UniCredit's asset manager Pioneer, which ended up being sold to France's Amundi.
Caio is expected to be succeeded by the head of power grid company Terna, Matteo Del Fante, the sources said, though they warned there could be last minute changes.
Two of the sources said there were still discussions about who would become the new CEO of Terna, should Caio be replaced by Del Fante.
Leonardo has benefited from a radical overhaul led by CEO Mauro Moretti, who has cut debt and streamlined the company's business to focus on core activities.
But his position was undermined after he was sentenced in January to seven years in prison for his alleged role in one of Italy's worst train accidents.
Under Italian law, Moretti can appeal the sentence twice and will not have to serve any jail time until the process ends. Moretti said on Wednesday he had the backing of investors to stay on at Leonardo. (Additional reporting by Alberto Sisto and Francesca Landini; writing by Silvia Aloisi and Giulia Segreti; editing by David Clarke and Susan Thomas)