ROME, April 11 (Reuters) - Italy's ruling coalition on Tuesday failed to clinch a deal on key appointments at state-controlled companies, two people familiar with the matter told Reuters, as negotiations continue within the government.

Leading posts at energy companies Enel and Eni , aerospace group Leonardo, Italian post office Poste Italiane and power grid Terna are up for grabs, with rightist Prime Minister Giorgia Meloni seen as determined to put her stamp on key positions.

A deal was expected at a cabinet meeting on Tuesday, after Deputy Prime Minister Matteo Salvini said the administration was confident of wrapping up talks and announcing the boards of all the involved companies.

But after the meeting, one of the sources said some posts were still under discussion, including chairpersons, and more time would be needed.

Sources have said Francesco Starace, who has been chief executive of Enel since 2014 but has not found favour with Meloni's inner circle, will be replaced.

Stefano Donnarumma, currently at the helm of Terna, is seen as the most likely successor after winning Meloni's backing, the sources said.

Enel is one of the world's biggest players in renewable energy, with almost 60 Gigawatt (GW) of installed capacity.

However, sources have previously said the government was concerned about its debts, which hit around 60 billion euros ($65.44 billion) in 2022, up from 45.5 billion in 2020, when Starace was appointed for a third term.

Enel in November unveiled its updated strategy to 2025, pledging to cut net debt by 21 billion euros via asset disposals, while at the same time investing 37 billion euros and increasing installed renewable capacity by 21 GW.

Claudio Descalzi, who has also held his job since 2014, is seen as likely to stay as Eni CEO for another three years and become the longest-serving head of the state-controlled group since its foundation in 1953.

The veteran executive last year helped Rome secure alternative gas supplies as Moscow curtailed its flows to Italy following the Russian invasion of Ukraine.

Descalzi is expected to help the government with its ambition of turning Italy into a major shipper of gas from North Africa and the Mediterranean to the rest of Europe.

Despite having won plaudits from investors for financial results, Descalzi's strategy is still criticised by energy transition advocates, who say Eni should spend more to develop its green businesses.

Leonardo CEO Alessandro Profumo is another manager seen on the way out.

Sources have said Roberto Cingolani, a technocrat and former ecological transition minister in the government of Mario Draghi, is Meloni's favourite to replace him.

($1 = 0.9168 euros) (Reporting by Giuseppe Fonte and Angelo Amante; Editing by Alexander Smith and Bill Berkrot)