Political leaders condemn Tunisia attack

The nation's leaders have condemned a "terrorist atrocity" in Tunisia, in which an Australian-Colombian citizen was killed.

The NSW man - 28-year-old Javier Camelo - and his Colombian mother were among 20 people killed in the gun attack at the National Bardo Museum in the capital Tunis.

Five Japanese, four Italians, two Colombians, two Tunisians and one person each from France, Poland and Spain are also among the dead.

The shooters opened fire on the tourists as they got off a bus before chasing them into the museum.

"Plainly, this is a terrorist outrage," Prime Minister Tony Abbott told parliament on Thursday.

It was an attack by Islamist extremists on a fledgling democracy, which so far had been able to resist the kind of actions characterised by al-Qaeda and ISIL, he said.

Opposition Leader Bill Shorten labelled the attack an "act of murder" and praised Tunisian parliamentarians who refused to "cower in fear" while they were locked down by security forces.

"Instead they sang their national anthem in defiance," he said.

Foreign Minister Julie Bishop said Tunisia, like other nations in the region, was struggling with violent extremism.

An estimated 2000 foreign fighters had left the country to join the conflict in Syria and Iraq, she said.

"No nation is immune from this brutal Islamic ideology," Ms Bishop told parliament.

Speaker Bronwyn Bishop recalled her visit to the museum in 2014 when a guest of the Tunisian government.

She said Australian MPs could convey support for their parliamentary colleagues in Tunisia so they would persist in their ideals and not be dissuaded by terrorism.

Australians planning to go to Tunisia are being urged by the Department of Foreign Affairs and Trade to exercise a high degree of caution.