British businessman Richard Branson has joined calls for clemency for convicted foreigners on death row in Indonesia, as an Indonesian minister warned of a renewed influx of asylum seekers into Australia if it continues to push the issue.

Virgin founder Branson said on 11 March he and fellow members of the Global Commission on Drug Policy had written to Indonesian President Joko Widodo, calling the planned execution of up to 11 foreigners a barbaric and inhumane form of punishment.

"We've studied different national approaches in great depth and what we have learned is that treating drugs as a health issue, not as a criminal issue, it actually helps lower the number of drug deaths, it limits the spread of infectious diseases like HIV and AIDS or hepatitis C and it reduces drug-related crime, and it allows people who struggle with addiction to become useful members of society again," Branson told Australian Broadcasting Corp television.

The planned executions by Indonesia of the death row inmates, most of whom were convicted on drug smuggling charges, have been widely condemned internationally. The group includes citizens of Australia, France, Brazil, the Philippines, Ghana and Nigeria, as well as Indonesia.

Widodo, who has signalled a hard line on drug crimes, has stood firm against appeals for clemency, warning other countries to stay out of Indonesia's sovereign affairs. The executions have been delayed while a number of legal appeals remain outstanding.