On the day of her arrest at Bahrain International Airport, human rights activist Maryam al-Khawaja tweeted: "Overheard guards saying they are going to deport me. They keep saying I am not a citizen." Khawaja had travelled to Bahrain from Denmark on August 30 to support her imprisoned father, who'd just started a second round of hunger strike five days earlier.

Her case highlights the threat now confronting some Bahraini opposition activists: The removal of their citizenship and subsequent deportation.

Like her father, who is serving a life sentence on charges of trying to overthrow the government during pro-reform protests three years ago, Khawaja is also a staunch critic of the Bahraini ruling Al Khalifa monarchy.

For years the main opposition in Bahrain has campaigned for a greater role in government. There have also been complaints of discrimination from the country's Shia Muslim population, a charge the government denies. Inspired by other uprisings in the region, tens of thousands marched on the streets in February 2011, demanding change.

But with the help of neighbouring Saudi Arabia and the United Arab Emirates, Bahrain crushed the revolt. Dozens of people were killed, hundreds wounded and more than a thousand were arrested. The government alleges that the protesters attacked police and that soldiers were deployed to "protect the safety of the citizens".

Since then, there have been almost daily protests and anti-government activists continue to be arrested arbitrarily, tortured and imprisoned, often without a fair trial. However, security forces have been attacked by home-made bombs in recent months. In March, three policemen were killed in a blast, including a policeman from the UAE.

Khawaja's lawyer is confident that her citizenship has not been officially revoked. Mohammed al-Jishi told Al Jazeera that the incident at the airport was simply a scare tactic: "It's a lengthy procedure to remove the citizenship of anyone. The king himself has to agree to revoke the citizenship of any national. This must be published in the newspapers. But this doesn't apply to Maryam."

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But what might prove to be an empty threat to Khawaja, is a reality for other anti-government protesters and activists that have campaigned for political reform in Bahrain. On August 6, a court sentenced nine people to prison and ordered that all the defendants be stripped of their citizenship. The men are facing prison terms between 5 and 15 years on charges of spying for the Iranian Revolutionary Guard Corps, forming a terrorist organisation, and smuggling weapons into the country.

Speaking to Al Jazeera, the mother of one of the convicted men said that the charges against her son were false. "He was involved in protests, but that's it. He never attacked the police or anyone," said Khatoon Al Asfoor. "It's not fair that they removed his nationality. We're Bahraini, we're Bahraini."

Many of the Bahrainis that have had their citizenship annulled say they were not even informed by the government. "It was just by chance that I found out that my nationality was revoked. I was in London at the time and my wife called me and told me the announcement was made on Bahraini TV," said Jalal Fairooz, a former Bahraini politician, who was a member of the opposition al-Wefaq party.

Fairooz is among a group of 31 people that were deprived of their Bahraini citizenship in November 2012. He now lives as a political refugee in London.

Fairooz told Al Jazeera why he was targeted: "My job as an opposition figure was to defend the oppressed and to speak about the major violations of human rights. Of course at the time, there was a lot of killing and bloodshed against the innocent protesters in Bahrain. I was threatened by the Bahraini authorities over and over. I kept receiving calls on my mobile, calling me names and telling me to stop talking to the international media."

At the time, the Bahraini government issued a statement with the names of the 31 people whose citizenships were revoked saying that they had "caused damage to state security".

Fairooz said the decision to make him stateless was a violation of Bahraini law. "When someone's citizenship is removed, you have to go to the courts and also the king must issue the order. But in this case, the order was issued by the Ministry of Interior. This is against Bahraini law".

In the past, Bahraini citizens could only have their nationality removed if they were convicted of treason, or if they were granted citizenship by another country, without government consent. And as Fairooz said, King Hamad bin Isa Al Khalifa himself must approve the sentence. But provisions in the Citizenship Act were amended in July, making it easier for the interior ministry, with cabinet approval, to revoke the citizenship of an individual. Bahrainis can now be made stateless if a person "causes harm to the interests of the kingdom".

Mansoor al-Jamri, the editor-in-chief of Bahrain's al-Wasat newspaper, told Al Jazeera that the wording of the new provisions are too vague. "There has been another concept that has been included recently and they called it 'duty of loyalty' to the country. Who is to define someone has somehow satisfied the duty of loyalty?"

Repeated calls from Al Jazeera to the Minister of Information Affairs Sameera Rajab's office were not returned in time for publication.

RELATED: Bahrain activist Maryam al-Khawaja released

But revoking the citizenship of people considered to be outspoken government critics is not unique to Bahrain. In Kuwait, at least 15 people have been made stateless this year. A media owner and also an opposition politician, along with three of his family members, were stripped of their citizenship in June. The government said it revoked Ahmed Jabr al-Shemmeri's citizenship because he was a threat to the country.

Jamri also argued that revoking the citizenship of certain people is an order being used, not to protect the country, but to eliminate dissidents. "It's another punitive measure that has been added to somehow curb the number of opponents. And I believe it contravenes the international covenants on civil and political rights, which is obligatory for Bahrain because Bahrain ratified those covenants in 2006."

On September 7, Bahraini state media reported how the king received a report from the country's National Institution of Human Rights. The NIHR has been criticised for suppressing the abuses committed by the government. In the article, King Khalifa highlights Bahrain's "resolve to promote and protect human rights in line with international laws and conventions". But there was no mention by the king of rendering people stateless in the past few years.

On September 18, Khawaja was released from jail, but the charges of assaulting two police officers remain, and she's currently banned from leaving Bahrain. Khawaja's latest session on trial was held on October 1. A judge ruled to postpone it til November 1, while a decision on her travel ban is expected later



