"I am in favour of the execution of capital punishment to Afzal Guru," he told reporters at his ancestral town, Raghoharh in Guna district.
He, however, said that the decision on the execution would only be taken after the disposal of Guru's mercy plea.
The senior Congress leader accused the BJP of adopting double standards on the issue of capital punishment.
Singh alleged that while on the one hand the saffron party wanted Guru to be hanged, on the other, it was demanding remission in capital punishment awarded to the extremists of Punjab.
