MELBOURNE, Australia - A handful of extremists with ties to an al-Qaida-linked group in Somalia planned to storm one of Australia's largest military bases and launch a fight to the death with troops, police said Tuesday.
Police revealed details of the alleged plot after arresting four suspects - Australian citizens aged between 22 and 26 with Somali and Lebanese origins - in pre-dawn raids Tuesday on 19 houses in the southern city of Melbourne, the culmination of a seven-month intelligence operation.
A fifth man already in custody on an unrelated assault charge was also being questioned about the plot, police said.
"Potentially this would have been, if it had been able to be carried out, the most serious terrorist attack on Australian soil," acting Australian Federal Police chief Tony Negus told reporters.
Prime Minister Kevin Rudd said the plot underscored that Australia is still under threat from extremist groups at home and abroad.
"Australians will be concerned to hear about arrests of this nature in our midst," Rudd told reporters in the northern city of Cairns. "This is a sober reminder that the threat of terrorism to Australia continues."
Only one of the four suspects was charged, Nayef El Sayad, and he appeared briefly in court on a count of conspiring with four others to plan a terrorist attack. He did not enter a plea or seek bail. He faces life in prison if convicted.
Police allege the cell's plan was to send a team of gunmen with automatic rifles on a suicide attack against Holsworthy Barracks, an army base on the outskirts of Australia's largest city, Sydney, that houses commandos trained in counterterrorism, a Black Hawk helicopter squadron and thousands of regular troops.
"Details of the planning indicated the alleged offenders were prepared to inflict a sustained attack on military personnel until they themselves were killed," Negus said.
Police said extensive electronic surveillance and phone intercepts of the cell revealed details of the plot.
"I stalked around. It is easy to enter" the Holsworthy barracks, one of the suspects allegedly said to another in an intercepted text message, The Age newspaper reported, citing police agent David Kinton.
Police did not allege a possible motive for the attack, or when it was planned for, but said the men were linked to the Somali Islamist organization al-Shabaab and were trying to find a senior cleric who would approve the operation so they could become martyrs.
Terrorist violence is extremely rare in Australia - the unsolved 1978 bombing near the Hilton Hotel that killed two is the best-known incident - and no attacks have been carried out in the country since the Sept. 11, 2001, attacks in the U.S. raised security threat levels worldwide.
But dozens of Australians have died in terrorist attacks overseas, mostly in Indonesia, including the 2002 Bali nightclub bombings.
The purported Somali-linked plot is the second major co-ordinated attack plan exposed in Australia in recent years. Seven men were imprisoned in the past year for a nascent plot to target thousands of spectators in an attack on a big sporting event in Australia.
Australia became a staunch U.S. ally in the war on terrorism after Sept. 11 and has deployed forces to fight insurgents in Afghanistan.
Asked if the deployment was making the country a terrorist target, Rudd said his government would not be swayed from the fight in that country because "we must deal with where the terrorists are trained."
Negus said some of the suspects had travelled to Somalia and were believed to have fought alongside Islamic insurgents there.
Al-Shabaab has been fighting to overthrow Somalia's Western-backed transitional government. It has claimed responsibility for several high-profile bombings and shootings in the Somali capital of Mogadishu, targeting Ethiopian troops and Somali government officials.
Washington has designated al-Shabaab as a terrorist group and says it has provided safe havens to al-Qaida "elements" wanted for the 1998 bombings of the U.S. embassies in Kenya and Tanzania that killed 236 people. The two groups have long been suspected of working together, but they have not announced a formal alliance.
Muslim leaders in Australia worried that news of the alleged plot could provoke ire toward the country's more than 340,000 Muslims.
"There are fears that there will be a backlash against the Muslim community and the Somali community," said Shereen Hassan, vice-president of the Islamic Council of Victoria state. "But we have faith that the overwhelming majority of Australians will not react in this way and remain calm."
Police conducted intensive searches for hours at houses raided Tuesday. Forensic officers in protective suits collected samples and searched at least one car parked in a driveway, while uniformed officers interviewed neighbours. Police did not say whether any firearms were seized.
Sayad was charged with conspiring with four unnamed people to plan a terrorist act. Magistrate Peter Reardon ordered him to remain in custody and reappear in court on Oct. 26.
Police were granted a court application to hold the other three suspects without charge until Wednesday for questioning.
Sullivan and Associated Press Writer Kristen Gelineau contributed to this report from Sydney.