TOKYO (Reuters) - A junior member of Japanese Prime Minister Shinzo Abe’s government resigned on Friday after making a gaffe seen to make light of the burden borne by people on the southern island of Okinawa as a reluctant host to the U.S. military, media said.

The resignation of Fumiaki Matsumoto, deputy minister of the Cabinet Office, will likely give Abe a fresh headache as the scandal comes ahead of a key mayoral election in Okinawa.

When an opposition lawmaker asked Abe in Thursday’s parliamentary session about a recent series of emergency landings by U.S. military helicopters in Okinawa, Matsumoto heckled by saying, “How many people died from that?” Kyodo news agency said.

Matsumoto on Friday tendered a letter of resignation, which Abe accepted, Kyodo said. No one was immediately available for comment at Matsumoto’s office or at the Cabinet Office.

In the Feb. 4 election in the city of Nago, incumbent Susumu Inamine, a staunch opponent of a plan to move the U.S. Marines’ Futenma airbase, located in another part of the island, to his city, is set to fight a candidate supported by Abe’s Liberal Democratic Party.

Abe’s government and Okinawa authorities have been at loggerheads for years over the relocation plan as resentment has simmered among residents who say they bear an unfair burden in supporting the U.S. military presence in Japan.

Many Okinawa residents associate the U.S. military presence with crime, pollution and accidents. A window fell from a U.S. helicopter onto a school sports field on the island last month, fanning safety concerns.

This is not the first time Abe has seen his minister resigning over missteps.

Last July, Tomomi Inada stepped down as defense minister after a series of gaffes and a cover-up at her ministry that contributed to a plunge in public support for the prime minister. But his support bounced back after a cabinet reshuffle in August.