Indonesia's embassy in Australia was closed Wednesday after a package containing what authorities described as a "biological agent" was delivered there. Officials linked the incident to outrage over the conviction in Bali of an Australian woman on drug charges.

Prime Minister John Howard (search), who apologized to Indonesia for the incident, said the agent was a powder sent in an envelope addressed to the Indonesian ambassador, Imron Cotan.

"It would be the first time if the preliminary results are confirmed, such a biological agent has been sent in Australia," Howard told reporters.

He said that if tests proved the powder was dangerous, "it's an act of reckless indifference to human life and I apologize on behalf of the Australian people to the Indonesian embassy and to the Indonesian government."

"The advice I have is that the reference 'biological agent' does not mean it is benign," he said.

In Indonesia, Foreign Ministry spokesman Marty Natalegawa told Metro TV station: "We want to stress that we will not be intimidated by this act."

By Wednesday afternoon, the leafy street outside the embassy had been cordoned off by federal police and fire fighters and ambulance staff were milling around outside. The street is in a neighborhood dotted with diplomatic posts — the U.S. embassy is only about 100 yards from the Indonesian embassy, but was not affected by the evacuation. The French embassy is next door.

Police superintendent Mick Kilfoyle said some embassy staff were being decontaminated inside the building. He declined to speculate on a motive.

Most staff were expected to be released later in the day, Kilfoyle said. Earlier, Foreign Minister Alexander Downer told Parliament the incident meant it was possible "the Indonesian Embassy will be shut down for quite some period of time and the 22 staff will remain in isolation for the next 48 hours."

Downer gave no details on the nature of the biological agent, but he blamed the security scare on public anger over the conviction in Bali, Indonesia last week of an Australian woman on drug smuggling charges.

The embassy had earlier received threats and requested additional security ahead of the conviction of 27-year-old Schapelle Corby (search) who was sentenced to 20 years in prison Friday for smuggling 9 pounds of marijuana to the Indonesian resort island of Bali (search) in October last year.

"We condemn this sort of abuse and we urge people who are concerned about Schapelle Corby to ensure they put their energy into supporting (her) legal defense team," Downer said.

Howard echoed the Downer's words, saying the situation "will do great damage in the eyes of many Indonesian people to the relationship between our countries and it certainly won't help Schapelle Corby."

Corby pleaded innocent and is appealing her conviction.