Lindsay Sandiford is the second British citizen to be sentenced to death for drug offences in Indonesia in recent months, according to human rights campaigners.
Amnesty International said British roofer Gareth Cashmore, 33, reportedly from Wakefield, West Yorkshire, was sentenced to death by firing squad last year in Indonesia.
He and Sandiford are among around 40 foreigners - most of them convicted of drug crimes - out of more than 100 prisoners on death row in the country.
"They have not actually executed anyone (in Indonesia) for three years, there have been no executions since 2008, but at least 100 people remain under sentence of death, that is obviously of great concern," a spokeswoman for Amnesty said.
"We are calling on Indonesia to commute all existing death sentences and impose instead an official moratorium instead of the unofficial one that has been in place since 2008."
According to Amnesty, more people are sentenced to death for drug offences than for any other crime in Asia-Pacific countries, with 16 countries sentencing people to death for drug trafficking and possession.
Worldwide, the number of executions has fallen by more than a third over the last decade, according to the organisation, with 21 out of 198 countries carrying out executions in 2011.
Death sentences were pardoned or commuted in 33 countries, compared to just 19 in 2010.
But Amnesty added that an "increasingly isolated" group of countries carried out executions at an "alarming rate" in 2011.
China continued to put thousands of people to death, and in the Middle East there was a sharp rise in the number of people executed in Iran, Iraq and Saudi Arabia, according to campaigners.
States that year-on-year figured "consistently" among the top executioners included North Korea, Saudi Arabia, Somalia, USA and Yemen, it added.
At least 18,750 people remained under sentence of death at the end of 2011 and at least 680 people were executed worldwide that year, excluding China, according to Amnesty.
The Foreign Office said it was aware of 12 British citizens across the world who have been sentenced to death.