Amnesty International has raised concerns that the Court of Appeal's decision to dismiss DAP national publicity secretary Tony Pua’s challenge against his 2015 travel ban may be politically motivated.

The human rights watchdog referred to the July 5 Court of Appeal ruling that the government has absolute discretion to bar any citizen from travelling abroad without giving any reason or notice.

"Amnesty International is concerned that the court's decision is politically motivated.

"The ruling comes at a time when the government is escalating its crackdown on dissent, with growing numbers of Malaysian political figures and human rights defenders being barred from leaving the country without any explanation," it said.

Justice Idrus Harun, who led the three-member bench, said in his 44-page judgment that there are no absolute rights in the Federal Constitution, including the right to travel abroad.

The judge also referred to the last page of the Malaysian-issued international passport, which states that the passport is the property of the Malaysian government and may be withdrawn at any time.

However, Amnesty International noted that the ruling allowing arbitrary travel bans would continue to hamper the work of human rights defenders, such as cartoonist Zunar, Bersih chairperson Maria Chin Abdullah and activist Hishamuddin Rais - all of whom have been unable to leave the country for more than a year.

"The crackdown has involved a slew of arrests under draconian colonial-era laws, severe restrictions on the human rights to expression and peaceful assembly and, most recently, a trend of imposing travel bans on human rights defenders and government critics," Amnesty International said.

"Travel bans against human rights defenders further stigmatises their work and severely harms their ties with the global human rights movement," it further said in urging Malaysian authorities to stop using open-ended arbitrary travel bans to threaten and restrict the movement of political figures and human rights defenders.

Not only are Malaysians being barred from travelling abroad, Amnesty International also pointed out that Singapore human rights defender, Han Hui Hui, was barred from entering the country last month after being labelled as an "undesirable immigrant" by the home minister.

"In recent years, Hong Kong political activist Joshua Wong and Indonesian human rights defender Mugiyanto Sipin have also been prevented from visiting the country," it added.

As such, Amnesty International called on the Malaysian authorities to respect and protect the rights to freedom of expression, association and movement, including by removing travel restrictions that violate internationally recognised human rights or have been imposed without due process.