Jihadists deserve what they get:Iran envoy

Australian jihadists caught fighting for Islamic State deserve whatever they get, Iran says.

There are concerns Iran may torture captives to glean information for Australian authorities under an unprecedented new intelligence-sharing deal aimed at tracking foreign fighters.

But Iran's ambassador to Australia could not guarantee their safety if they are intercepted by its operatives.

Abdolhossein Vahaji said the bigger picture was the defeat of IS, a cause for which Australia has pledged another 300 troops to train Iraqi forces.

The nationality of the fighters didn't matter, because they were threatening the security of the region.

"Whatever they get, they deserve to get it," the ambassador told ABC radio on Tuesday.

Mr Vahaji also hit back at critics of his country's human rights record, saying Australia had also been condemned for its treatment of asylum seekers.

Iran has agreed to take back failed asylum seekers returning voluntarily, but not those forcibly deported.