Australia's Foreign Minister Julie Bishop walks with her Iraqi counterpart Ibrahim al-Jaafari
Australia's Foreign Minister Julie Bishop walks with her Iraqi counterpart Ibrahim al-Jaafari (not in picture) in Baghdad October 18, 2014. Bishop arrived in Baghdad for talks with Iraqi officials on Australia's role in the fight against Islamic State. REUTERS/Ahmed Saad

Australia has become an important supplier of foreign fighters to Syria and Iraq. The number of Australians going to the Middle East to join militants is higher than other countries.

The Australian Security Intelligence Organisation told a Senate inquiry that a successful attack on Australian soil would be considered a "propaganda victory" for extremists. The ASIO deputy director general, Kerri Hartland, said security agencies in the country have been previously warned about the possibility of a well-planned terror attack with high casualties, The Guardian reported.

According to Hartland, launching a random attack using simple weapons was more likely to happen, following the threats issued by ISIS. If ever ISIS would attack in Australia, it would only bring the extremist group "great propaganda mileage." The Australian security agency revealed that it has identified around 70 Australians currently in Iraq or Syria fighting alongside extremists.

ASIO said there are at least 3,000 Western fighters in the Middle East and 20 Australians have already died in the conflict. Hartland added that ASIO is monitoring about 100 people in Australia who are suspected of supporting and providing materials to extremists. Some Australians are reportedly recruiting fighters for ISIS and giving funds, reports said.

Hartland told the inquiry that ASIO has seen a greater number of Australians fighting than from other countries. She said Australia is a "significant source country" based on the number of people fighting in Iraq or Syria. ASIO is currently conducting an evaluation on why people are drawn to extremism. However, Hartland noted many people fighting on foreign land are second or third-generation Australians.

The Australian government has previously announced a plan to cancel the passports of Australians who went to the Middle East to join ISIS. Hartland said the threat would not prevent Australian citizens who are suspected of fighting overseas to return to the country.

Attorney General George Brandis said Australians with cancelled passports can still return to Australia if they want and if they receive a single travel document. He stated that Australian citizens have the right to return to their home country regardless of their passports.

ISIS militants have been using Australians and other Western fighters as suicide bombers, cannon fodders and propaganda tools in the fight against the U.S.-led coalition, The Daily Mail reported. Brandis said the number of dead Australian fighters has increased in the last few weeks as fighting in Iraq and Syria intensifies.