At least a dozen distinct groups are believed to be operating, the most feared, known as Aitarak or Thorn, is headed by Mr Guterres. Some of the militias can be traced to 1975 when Indonesia invaded East Timor and began arming groups to help bolster the union with Jakarta.
The Suharto regime in Indonesia used the militias to help it to counter the threat of rebellion from Falintil, the pro-independence guerrillas. Other militias have surfaced since the change of regime in Jakarta and the preparations for the referendum. The Indonesian military is believed to be arming the militias, which have killed at least 1,000 civilians in the past year.