* Egypt stepping up use of travel bans against dissidents
* Six government critics stopped at airports in one week
* U.N. says bans part of wider crackdown on civil society
By Ahmed Aboulenein
CAIRO, Dec 2 (Reuters) - Azza Soliman was due to board a plane to attend a conference in Jordan when security officials at Cairo airport turned her away, saying a court order banned her from travelling.
The veteran human rights lawyer and feminist was one of at least six activists, lawyers and journalists prevented from leaving Egypt in the space of a week.
Rights groups say 217 people were banned from travel between June 2014 and September 2016 -- 115 of them government critics.
They see restrictions as part of a wider move by President Abdel Fattah al-Sisi to silence opponents and erase freedoms won in the 2011 uprising that ended Hosni Mubarak's 30-year rule.
Soliman said she discovered after being turned back at the airport on Nov. 19 that her personal assets and those of her non-governmental organisation (NGO) had been frozen, even though she was not aware of any legal case against her.
"We are in a state that tramples on the law and constitution. They are acting like thieves in the night," she told Reuters. "I wasn't shown a single official paper saying I've been banned from travel or that my assets were frozen."
Four days later on Nov. 23, officials banned from travel a veteran activist who runs a centre that rehabilitates torture victims and a journalist who aired a television segment critical of the government. Another journalist was banned on Nov. 24 and a prominent women's rights campaigner on Nov. 25.
The rash of travel bans prompted a rebuke from the United Nations Special Rapporteur on human rights defenders, who said they were part of an effort to silence critics.
"Restrictions imposed on...freedom of movement have regrettably become routine in what is seen as a broader crackdown against Egyptian civil society that has continued unabated since 2011," Michel Forst said in a statement.
An Interior Ministry spokesman said police do not stop anyone from travel unless a court or prosecutor has ordered it.
"It is not the airport security officer's job to tell people why they are banned," he said.
Airport security officials echoed those points but said that when prominent activists attempt to travel, passport control can consult security or intelligence agencies who sometimes order people stopped.
The Interior Ministry denied there was a government crackdown.
But Egypt's human rights record is coming under increasing scrutiny, inclduing from close ally the United States.
The U.S. State Department's 2015 rights report, released in April, highlighted restrictions on academic freedom and civil society as well as the impunity for security forces who torture and kill.
U.S. Secretary of State John Kerry said in March he was deeply concerned by the deterioration in rights, including the decision to reopen an investigation of NGOs which were documenting abuses.
U.S. House of Representatives Speaker Paul Ryan said in April Egypt's human rights record made it more difficult to support Cairo. But U.S. President-elect Donald Trump spoke last month of his admiration for Sisi and called the Egyptian president "a fantastic guy."
Human Rights Watch and Amnesty International, in a joint statement in November, urged Egyptian authorities to stop imposing the travel bans on human rights defenders.
"The Egyptian authorities want to sever the connection between the Egyptian human rights movement and the outside world," said Joe Stork, deputy Middle East and North Africa director at Human Rights Watch.
Amnesty said the authorities were using the bans to intimidate human rights defenders and hamper their work.
Mohamed Zaree was on his way to a workshop in Tunis in May when he was turned back from the airport. The Cairo Institute for Human Rights Studies, where he works, is among several rights groups facing investigation in a 2011 case, accused of taking foreign funds to sow chaos.
But Zaree has not been officially charged and received no explanation for or prior notice of any travel restrictions.
"This whole thing is very Kafkaesque. I don't know why I am banned or by whom, I don't know where to get any official notice," he said, referring to the Franz Kafka novel "The Trial" in which the protagonist is tried in mysterious circumstances.
"I feel like the entire country is a giant prison I cannot leave, and I am not sure how long my sentence is."
Hundreds of Islamists have been killed and thousands jailed since Sisi seized power in mid-2013, promising stability after a divisive year of Muslim Brotherhood rule. But the dragnet has since widened to include secular activists who opposed the Brotherhood but clung to hopes of political change.
Parliament passed in November a law regulating NGOs, which human rights groups say effectively bans their work and makes it harder for development groups and charities to operate.
One of its provisions jails NGO workers for collaborating with international institutions like the United Nations without prior permission.
Rights lawyers and NGO workers said they now feared the travel bans could be used to intimidate them whether or not they had broken any law.
Malek Adly, a human rights lawyer who was banned from travel earlier in November, said he was given no explanation.
Part of a legal team trying to block the transfer of two Red Sea islands to Saudi Arabia, Adly said he believed he was targeted because of his opposition to Sisi.
"I was neither given nor shown any official paperwork saying I am banned from travel," he said. (Additional reporting by Stephanie Ulmer-Nebehay in Geneva, Editing by Lin Noueihed and Angus MacSwan)