Amnesty International said Thursday that Malaysia was preparing to put a condemned man to death, and called on the government to halt "yet another secretive execution".
The London-based human rights group said in a statement it had learnt that the man would be executed Friday for a murder committed more than a decade ago. It identified him only by the name "Chandran".
But HINDRAF, a group that advocates for the rights of Malaysia's ethnic Indian minority, said his name was Chandran Paskaran. HINDRAF also called for him to be spared.
The government of Muslim-majority Malaysia does not announce executions and is generally tight-lipped about its application of the death penalty.
"Malaysian authorities must immediately halt plans to carry out yet another secretive execution," Amnesty said in a statement.
The statement quoted Hazel Galang-Folli, Amnesty's Malaysia researcher, as saying the execution would be "an enormous step backwards on human rights".
Government officials did not immediately respond to AFP queries.
An official said in 2012 that about 900 people were on death row, mostly for drug offences.
However, Malaysia is believed to have carried out few executions -- which are done by hanging -- in recent years.
In 2012 a government minister said it may reconsider a mandatory death sentence for drug trafficking, but nothing further has been announced.
"For Malaysia to try to carry out executions in near-total secrecy is shameful -- the government is essentially trying to hide its human rights violations from the world," Galang-Folli said.
"With yet another scheduled execution, the authorities are undoing any positive steps taken, including the announcement of the legal review of mandatory death sentences."
Between 1960 and 2011, nearly 450 people were executed, according to data released in 2011.
Two Australians were put to death in 1986 for heroin trafficking -- the first Westerners to be hanged.