Rostom Ghazali, the powerful Syrian general who was once considered the most powerful man in Lebanon and was suspected of involvement in the 2005 assassination of a former Lebanese prime minister Rafik Harriri, has died in a hospital in the capital Damascus, a Syrian activist and local media reported on Friday.

Ghazali, in his early 60s, was once head of his military's powerful political security branch and one of Syrian President Bashar Assad's most trusted generals.

There was no official government comment and the circumstances of his death remain unclear.

Director of the Britain-based Syrian Observatory for Human Rights Rami Abdurrahman said Ghazali died nearly two months after he was admitted with a head injury. Abdurrahman said Ghazali had been clinically dead for weeks, quoting informed medical officials in the hospital.

The Beirut-based Al-Mayadeen TV, which has access to Syrian officials, and other Lebanese TV stations also reported Ghazali's death, quoting officials.

Reports at the time of Ghazali's injury said he was beaten by the bodyguards of another Syrian general, in a dramatic escalation of a political dispute.

The reports said the disagreement between the two generals started after Ghazali's men were not allowed to play a bigger role in a government offensive, in which Lebanon's Hezbollah fighters took part, against opposition fighters battling the government.

Lebanese media reported that both Ghazali and his rival general were sacked. Reshuffles in Syria's security and military apparatuses are generally not made public.

In 2005, a U.N. probe concluded that high-ranking Syrian and Lebanese security officials, including Ghazali, plotted the assassination of Hariri in a complex operation. A U.N.-backed tribunal is currently trying five Hezbollah members in absentia over Hariri's assassination. Both Damascus and Hezbollah have strongly denied involvement.

Meanwhile, Syrian state TV said a plane on a training mission in the country's south crashed because of a technical failure and the pilot is missing. The Observatory however reported that Islamic State fighters downed the plane.

There was no way to independently verify the reports.