Indonesia has asked foreign embassies to send representatives to a maximum security prison ahead of the expected execution of 10 drug convicts, although an official 72-hour notice of execution has not been given yet.

Among the convicted drug offenders set to face the firing squad are nationals from Australia, Brazil, France and Nigeria and the case has strained relations between the governments of those nations and Indonesia.

The Attorney General's Office said it expected to announce the date of execution in the next few weeks.

Embassy officials received text messages from the government to send representatives on Saturday to the prison island of Nusakambangan, where the executions will soon take place. It was not clear why they were being summoned so early.

Security at the prison has been heightened and religious counsellors, doctors and the firing squad were alerted to start final preparations.

The Attorney General has been waiting for all the legal processes of the 10 death row inmates to be completed before announcing an execution date.