An Egyptian court on Wednesday adjourned the murder trial of deposed president Mohamed Morsi to February 1, citing "weather conditions" that prevented the Islamist's transport to court from prison.
It had been scheduled as the second hearing in Morsi's trial, after an initial court appearance in November in which he denounced the tribunal and insisted he was still the country's president.
Morsi, who was toppled by the military in July, is accused of inciting the killings of opposition protesters in December 2012 outside the presidential palace.
"Because of the weather conditions, Mohamed Morsi could not be brought, so the trial will be adjourned to February 1," said presiding judge Ahmed Sabry Youssef.
Morsi is held in prison some 60 kilometres (40 miles) from the Mediterranean city of Alexandria.
Interior minister Mohamed Ibrahim said the pilot of the helicopter that was meant to transport Morsi refused to set off because of "bad weather conditions and heavy fog in Alexandria," the state news agency MENA reported.
Morsi's Muslim Brotherhood in a statement said the minister's excuse was "risible" and accused authorities of holding him in an undisclosed location.
One of Morsi's lawyers told AFP he had not been allowed visits to the ousted leader for a month.
An official at the Burj al-Arab airport close to the prison said there was heavy fog in the area on Wednesday morning but that no flights were affected.
Morsi is on trial with 14 co-defendants, but only some of them were brought Wednesday to the makeshift courthouse in a police academy on Cairo's outskirts.
Police, meanwhile, fired tear gas at Morsi supporters who had rallied in protest at the trial.
In Cairo's Nasr City neighbourhood, tyres were burnt and some car windows were smashed during brief clashes.
The interior ministry said 17 people had been arrested.
In the police academy, defendants were held in a room adjacent to the court room as they waited for the hearing to start.
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"This is a political trial," yelled Essam al-Erian, a senior member of the Muslim Brotherhood, who was among the defendants.
His lawyer Bahaa el-Din Abdel Rahman told AFP his client and other defendants had embarked on a hunger strike.
"All the accused who are present today are on hunger strike and reaffirm that they reject this trial," he said.
Morsi's trial is seen as a test for Egypt's new authorities, who have come under fire for heavy-handedness.
With more than 1,000 people killed since Morsi's overthrow and thousands of Islamists arrested, the chances of political reconciliation in the Arab world's most populous nation are ever more remote.
Morsi will also face separate trials on charges of espionage and colluding with militants to carry out attacks in Egypt.
He was catapulted from the underground offices of the long-banned Muslim Brotherhood to become Egypt's first freely elected president in June 2012 following Hosni Mubarak's overthrow in an early 2011 uprising.
But his single year in power was marred by political turmoil, deadly clashes and a crippling economic crisis.
In December 2012, members of the Muslim Brotherhood attacked opposition protesters camped outside the presidential palace in protest at a decree by Morsi to grant himself extra-judicial powers.
At least seven people were killed in the clashes, and dozens of opposition protesters were detained and beaten by Morsi's supporters.
The incident was a turning point in Morsi's presidency, galvanising a disparate opposition that eventually organised mass protests in June 2013 that prompted the military to topple and detain him.
Morsi's defence says there is no proof he incited the clashes, and that most of those killed in the violence were Brotherhood members.