A Diet members' group formed to end the death penalty plans to resume operations as early as next month after suspending its activities following the 2012 election, sources said Monday.

The group headed by Shizuka Kamei, 77, an independent in the Lower House, wants to establish a new prison sentence — life with no chance of parole — to make taking capital punishment of the books easier, the sources said.

Alarmed by the execution of nine inmates since Prime Minister Shinzo Abe took power following the Lower House election in December 2012, Kamei, a former police officer who once headed the now-defunct Kokumin Shinto (People's New Party), and other group members have called on ruling and opposition lawmakers in both Diet houses to join the parliamentary body, the sources said.