A military court in Cairo has sentenced an Egyptian army colonel to six years in prison after he announced his plans to run for president next year, according to his lawyer and local media.
Ahmed Konsowa was given the jail term on Tuesday for "stating political opinions contrary to the requirements of military order", his lawyer, Asad Haykal, was quoted as saying by AFP news agency.
Following his detention, Haykal told local media that the charges against Konsowa included violating military code and publishing a video in which he espoused political views.
In last month's video, Konsowa, who was donning his military attire, said that he was "proudly" declaring his candidacy.
"I have decided to unlock the current political deadlock," he said.
In his announcement, the colonel also said that he had been attempting to resign from his army position since March 2014, but that his "resignation had not been accepted".
"It's not a secret that I've spent more than three years and a half in courts, suing the government in 11 lawsuits, struggling in a very disappointing legal battle, to get my political-participation constitutional right to run for various elections."
Konsowa also said the country was witnessing "crucial circumstances" with the "threat of terrorism" and criticised what he called "inappropriate, counterproductive and outdated policies" which "fuel extremism and discontent in the most populous nation in the tumultuous Middle East".
Egypt is due to hold presidential elections in March or April next year.
'Antithesis of Sisi'
A former army chief, el-Sisi led a military coup in July 2013 to overthrow Mohamed Morsi, Egypt's first democratically-elected president, following mass protests.
Two years earlier, during a wave of popular uprisings that swept across the Arab world, the Egyptian people had overthrown the 30-year dictatorship of President Hosni Mubarak, in what became known as the January 25 revolution.
In March 2014, el-Sisi resigned from the army as he declared his candidacy for a presidential election later in the year, which he won in a landslide.
The political and social upheaval of the past six years has plunged the country into an economic crisis and given rise to deep divisions.
Under el-Sisi, Egypt has imposed a wide crackdown on dissidents, including a law banning demonstrations without prior police approval. The government has also passed legislation criminalising the work of many non-governmental bodies, placing them under the direct surveillance of the country's security apparatus.
A Cairo-based political commentator, who has asked to remain anonymous for fear of reprisals, said he believes Konsowa was sentenced "because in Egypt there can be no real power-sharing or transfer of power".
"Egyptians love their military and so to have someone competing from within the military may divide it," he told Al Jazeera.
"Ahmed Konsowa is the antithesis of Sisi - he's smart, well spoken, educated and supports the January 25 revolution. He presents Egypt with an alternative ... and the idea that an alternative may exist is threatening to the Egyptian regime," he said.
Along with Konsowa, both Ahmed Shafik, the country's former prime minister, and Khaled Ali, a prominent lawyer, have voiced their intent to challenge Sisi in the upcoming elections.
Hours after announcing his plans on November 29, Shafik said in an exclusive video message to Al Jazeera that he had been blocked from leaving the United Arab Emirates (UAE), where he had been residing since 2012, for reasons that he did not know or understand.
Earlier this month, Shafik was deported from the UAE, returned to Egypt and said he was still considering running for election.
Ali, who is seen as el-Sisi's top competition, was also convicted in September on charges of public indecency - a move that rights groups condemned as "politically motivated" to eliminate the president's rivals in the elections.
Ali has since appealed, but if the conviction is upheld, he could be disqualified from running in the elections.