Wireless carriers tumbled in Tokyo after the government's spokesman said they have room to cut phone bills by about 40 percent, sparking concern that lawmakers will renew a push for greater competition in a sector dominated by three big players.

The declines wiped about ¥1 trillion ($9 billion) in market value off the three largest carriers combined after Chief Cabinet Secretary Yoshihide Suga made the comment during a speech in Hokkaido, Japan. He said competition isn't working at the companies. Kyodo News earlier reported the remarks, which were confirmed by Suga's office.

NTT Docomo Inc. fell 4 percent, the biggest drop this year, while KDDI Corp. declined 5.2 percent and SoftBank Group Corp. slipped 1.6 percent at the close of Tokyo trading.