John Kerry flies in for surprise visit day before ex-president is due to be tried for inciting murder of opposition demonstrators

Egypt's former president Mohamed Morsi plans to reject the authority of a court due to try him on Monday, in what could be his first public appearance since being deposed and hidden in a secret location in July.

The trial is expected to increase Egypt's political tensions, with Morsi supporters planning a series of nationwide protests and police announcing a state of alert. Security fears are so high that on Sunday court officials had not yet confirmed whether the trial would be televised, or even whether the ex-president would be allowed to attend in person.

Morsi stands accused of inciting the murder of protesters demonstrating outside Cairo's presidential palace last December, charges also faced by 14 other senior officials from the Muslim Brotherhood.

Morsi, who still regards himself as Egypt's legal president, plans to defend himself because he believes engaging a lawyer would be an indirect acknowledgment of the court's authority.

"Neither us nor President Morsi acknowledges the legitimacy of this trial," said Amr Darrag, a cabinet minister during Morsi's year in office, speaking on behalf of the Muslim Brotherhood's political wing, the Freedom and Justice party.

Morsi's trial is likely to spark renewed unrest. A spokesman for the anti-coup alliance – a coalition of Morsi backers from the Brotherhood and its allies – has promised to "make this day an international day of protest. We will defeat this brutal traitorous military coup."

More than 1,000 pro-Morsi supporters and dozens of security officials have died during confrontations at protests since Morsi's 3 July overthrow. Terrorist attacks by Islamist extremists have also risen.

Fears that Morsi's re-emergence might reinvigorate his supporters have led Egypt's authorities to keep quiet about the precise arrangements for his trial. While it is likely to take place at a police compound on the eastern outskirts of Cairo, this has not been officially confirmed. An official at the prosecutors' office told the Guardian it had not yet been decided whether the trial would be televised orwhether Morsi would be allowed to attend, out of fear for public order.

In news that may exacerbate tensions further, the US secretary of state, John Kerry, arrived in Egypt on Sunday – the first time a US secretary of state has travelled to Egypt on what is known as an unannounced visit for security reasons.

A US official said Kerry's visit was entirely unrelated to Morsi's trial, but his presence could anger both Morsi supporters and his critics, who each accuse the US of meddling in Egyptian affairs and of siding with their opponents.

The US has never described Morsi's overthrow as a coup, but last month Washington cut the amount of aid it gives to Egypt. The unannounced nature of Kerry's arrival suggests he is keen to keep a low profile.

For the first time in its history, Egypt will have two ex-presidents on trial at the same time, with Morsi following his predecessor Hosni Mubarak into the dock. But whereas Mubarak's first trial (he is currently being retried) was greeted eagerly by most Egyptians, Morsi's prosecution has provoked mixed emotions.

"A lot of Egyptians feel pity for Morsi, even people who like Sisi [the army chief, General Abdel Fatah al-Sisi]," argued Ahmed Shabani, a 30-year-old doctor who took part in anti-Morsi protests this June, and who was also involved in the December demonstrations against Morsi that led to this trial.

"We know he was just a pawn for the Brotherhood, an engineering professor who became the president," Shabani added. "And now he's probably going to be sentenced to life."

In some quarters, the case is seen as a trial of the Brotherhood rather than just Morsi himself, said HA Hellyer, a Cairo-based analyst at the Royal United Services Institute, a foreign affairs thinktank.

"When Mubarak was in court, it was the prosecution of a president who'd been around for 30 years, and those who were very vigorously in support of the trial really wanted a death sentence," said Hellyer. "But with Morsi, it feels more like it's the Brotherhood on trial, rather than Morsi as an individual. I get the impression that as long as the Brotherhood get stamped out, it wouldn't go down so badly. I don't think they're looking for Morsi's blood."

Morsi and his co-defendants are accused of ordering hundreds of Brotherhood cadres on 5 December 2012 to attack secular protesters camped outside his presidential palace demanding the abandonment of a constitution drafted by Morsi's allies. The confrontation sparked night-long clashes that left at least 10 dead, and began a spiral of political upheaval that led the army to overthrow Morsi this July, following days of mass protests.

"It was a turning point in Egyptian history," said Shabani, the Morsi critic, of the December clashes. "For the first time two groups of people directly faced each other on the basis of their political beliefs. It was a civil war – a small one, just on one street. But ever since everything went violent."

Morsi was arrested along with several of his aides on 3 July, and has since been held virtually incommunicado in at least three government compounds. Beyond a visit from EU foreign affairs chief, Catherine Ashton, and two phonecalls with his family, his jailers have limited Morsi's contact with the outside world – treatment his supporters say is extrajudicial and does not bode well for a fair procedure in the courtroom.

"There is no evidence in Morsi's 4 November trial," Morsi's legal adviser, Mohamed el-Damaty, told Egypt's flagship state newspaper, al-Ahram.

But Egypt's new interim government says his treatment and his prosecution are legitimate. "He will have full rights to a free and fair trial," said Badr Abdellaty, a spokesman for Egypt's foreign ministry. "He will be charged on criminal charges before his normal judge according to the Egyptian penal code. Nothing extraordinary. Nothing exceptional."

Whatever else happens, Morsi's prosecution is unlikely to be speedy. Mubarak's trial was subject to frequent administrative delays and postponements. "If it's anything like Mubarak's trial, this session may start and finish within about five minutes," said Hellyer. "It could be the start of a very drawn-out process."