Malaysia detained an Australian politician at Kuala Lumpur airport Saturday, branding him a "prohibited immigrant" ahead of his expected deportation, in a move Canberra described as "disappointing".
Nick Xenophon, an outspoken independent Senator who has been critical of Malaysia's electoral system, was held at the international airport near the capital Kuala Lumpur upon his arrival from Melbourne.
He is expected to be deported later Saturday.
Immigration director general Alias Ahmad said in a text message to AFP that Xenophon had "tarnished the image of the country" and been classified as a "prohibited immigrant" under immigration laws, without elaborating.
Xenophon told ABC News 24 that he was informed he was a security risk. He and other Australian lawmakers were planning the Malaysia trip to try and ascertain the freeness of upcoming national elections, due by June.
The other lawmakers have reportedly cancelled their trip after Xenophon's detention.
Home Minister Hishammuddin Hussein was quoted by The Star daily online as saying foreigners denied entry in Malaysia was a "normal thing".
"Being a senator doesn't make him (Xenophon) special," he said.
Xenophon told AFP by telephone from the airport: "I think the Australian government has been incredibly silent about some of the abuses that have been occurring here in terms of the way the democratic system runs or doesn't run."
Australia's Foreign Minister Bob Carr said officials were in touch with Xenophon and were seeking his "swift release" and a "full explanation" of the incident.
"Senator Xenophon's detention is a surprising and disappointing act from a country with which Australia routinely maintains strong diplomatic relations," he said, adding that he had been in Malaysia for "peaceful purposes".
Xenophon has previously travelled to the country several times, including to study the polling system at the invitation of opposition leader Anwar Ibrahim.
On this visit he was to meet members of electoral reform group Bersih and others including Anwar and Election Commission officials.
Anwar condemned Xenophon's detention "in the strongest terms", saying allegations that he was a security threat were "completely without foundation".
"I would like to remind Prime Minister Najib Razak that he has no right to treat visitors as enemies of the state merely because they are critical of his... administration," he said in a statement.
The upcoming polls are expected to be the toughest ever test for Najib's coalition, which has ruled the country since independence from Britain in 1957 but has lost support in recent years.
Najib has touted reforms to boost the economy and allow for greater civil liberties, but rights group have dismissed the changes as window-dressing to get votes.
Malaysian Bar Council president Lim Chee Wee said in a statement Saturday that the bar is "astounded at the absurdity" of Xenophon's detention, calling for his release.
"Such shameful action on the part of the authorities shows the sizeable gulf between the aspirational statements of the prime minister that Malaysia is a modern democracy, and the irrational actions of the people around him," he said.