A letter written by a member of the Al Qaeda-linked Jemaah Islamiyah (search) terror network said the group is planning an attack similar to the 2002 Bali nightclub bombings, a top Singaporean official said.

Minister of Home Affairs Wong Kan Seng (search) said Indonesian authorities obtained the letter, but he did not elaborate further. Indonesia seized some documents after a homicide car bombing at the Australian Embassy in Jakarta (search) in September that killed 10, but it was unclear if the letter was among them.

"A letter recovered in Indonesia, written by a JI member, said that 12 operatives were ready to be martyrs and that plans for a Bali-style attack were underway," Wong said in a speech Monday evening to intelligence officials.

Wong said the letter reflected efforts of terrorists to overcome setbacks and stay a step ahead of the law by using different forms of communication.

"In order to communicate clandestinely, terrorists exploited the anonymity of prepaid phone cards and the Internet. However, when they suspected that these communications were being monitored and their activities and operatives compromised, they reverted to couriers and old fashion letter-writing," Wong said.

He also said terror groups have begun to use Caucasians and converts to Islam who do not fit stereotypical terrorist profiles.

"Especially valued are those operatives who hold passports of countries that enjoy visa-free facilities with a target country," he said.

Jemaah Islamiyah has been blamed for a host of attacks and plots throughout Southeast Asia, including the 2002 Bali nightclub attacks that killed 202 people, a blast at Jakarta's J.W. Marriott hotel the following year that killed 12, and the Australian embassy bombing.

Wong spoke at a promotions ceremony for Singapore's Internal Security Department, a clandestine unit that was largely responsible for breaking up an alleged plot by Jemaah Islamiyah to blow up the U.S. Embassy, a U.S. Naval facility and other Western targets in 2001. Nearly 40 alleged operatives were arrested.

"Our close relationship with the U.S., and our actions against the JI and Al Qaida, not only in Singapore but in cooperation with other countries, make us a priority target," Wong said.