The government and the ruling Liberal Democratic Party decided Friday to consider legislation that would force Diet members who are elected as a party's proportional representation candidate to step down if they leave their party, LDP Secretary General Taku Yamasaki said.

Embattled lawmaker Muneo Suzuki, elected as an LDP proportional representation candidate, is still a House of Representatives member although he left the party in March.

"Basically, Suzuki should have given up his Diet seat when he left the party," said Chief Cabinet Secretary Yasuo Fukuda during a regular news conference. "It is a loophole in the electoral system."