Officials recently started getting ready after an order from the attorney-general's office, which oversees executions, said Central Java police spokesman Aloysius Lilik Darmanto.
He said no date had been set for the executions, which will take place on the prison island of Nusakambangan in Central Java, and he did not know who would face the firing squad.
Indonesian President Joko Widodo has repeatedly insisted that drug traffickers must face the firing squad to stem rising narcotics use. There are scores of drug convicts on death row in the country, including Indonesians and foreigners.
There has been growing speculation in recent weeks that executions were set to resume after a year-long hiatus, but high-ranking officials in Jakarta have so far said little. There was no immediate comment Wednesday from the attorney-general's office.
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The execution in April last year of seven foreigners -- two Australians, a Brazilian and four Nigerians -- and an Indonesian for drug offences sparked international fury.
Since then, no one else has been put to death, but officials had continued to insist publicly that it was the country's right to use capital punishment.
A British grandmother, Lindsay Sandiford, is on death row in Bali after she was caught smuggling a huge stash of cocaine into the resort island.
Darmanto said preparations included ensuring locations where the executions would take place were ready. For last year's executions, the drug convicts were taken to a jungle clearing on the island, which houses several high-security prisons, and tied to stakes before being shot.
"We have also prepared the facility for the bodies," he said.
The executions last year of Australian drug smugglers Andrew Chan and Myuran Sukumaran in particular caused tensions, with Indonesia's neighbour Australia temporarily recalling its ambassador from Jakarta.