An Australian lawmaker who has criticised Malaysia's electoral system as unfair said Friday he has launched a court challenge against an entry ban that saw him deported from the country.

Independent senator Nick Xenophon landed in Kuala Lumpur in February to study the electoral system of Malaysia -- which is bracing for close polls next month -- but was barred entry at the airport and deported.

An application in the Kuala Lumpur High Court challenging the entry ban was filed on Thursday, his Malaysian lawyer Ranjit Singh told AFP.

"The Malaysian Government's actions were surprising, extraordinary and unwarranted, that's why I am challenging the orders deporting and banning me," Xenophon said in a statement.

He added that he "would very much like to be able to visit Malaysia again in the future".

Malaysia is bracing for what will likely be its closest ever election, with the Barisan Nasional coalition that has ruled since independence in 1957 facing an energised opposition.

Malaysia's government said Xenophon was barred entry because he took part in a 2012 mass rally for electoral reforms in Kuala Lumpur that ended with clashes between police and demonstrators, adding he had tarnished the country's image.

Australian lawmakers and Malaysian human rights groups and opposition leaders slammed the deportation, with Australian Prime Minister Julia Gillard saying she was "surprised and disappointed" by Malaysia's actions.

Activists say the vote's integrity is threatened by Barisan's stranglehold on mainstream media and an Election Commission they say is biased against the opposition. They also have warned the voter roll is full of irregularities.

The government denies the accusations, saying recent reforms including the introduction of indelible ink to prevent multiple voting will make this Malaysia's cleanest election ever.

Xenophon said he had written to Austriala's foreign minister for his support in challenging the entry ban.

Ranjit said he was still awaiting a date to present the application in court but that could be weeks away.