Taiwanese voters approved a referendum to maintain a ban on food products from five Japanese prefectures, imposed after the 2011 Fukushima nuclear power plant disaster, dealing a setback to the government of President Tsai Ing-wen and possibly damaging the island’s relations with Japan.

The Central Election Commission website showed that a total of 7.79 million people approved the initiative against 2.23 million who were in opposition.

The referendum result is legally binding and government agencies must take necessary action.

The result dealt a significant blow to the Democratic Progressive Party government that proposed easing the ban after coming to power in May 2016, but backed away when the main opposition Nationalist Party (KMT) questioned the new government’s ability to ensure the safety of the imported products.

Government officials responsible for the policy declined to comment on Sunday, only saying it was a matter for President Tsai to decide.

Tsai announced her resignation as DPP leader on Saturday following her party’s disastrous defeat in key mayoral elections that day, races viewed as indicators of voter sentiment ahead of the next presidential and island-wide legislative elections in 2020.

Some worry that the result of the referendum on Japanese food imports will have a negative impact on the island’s relations with Japan. Taiwan’s representative to Japan, Frank Hsieh, said the initiative was a KMT scheme aimed at undermining bilateral relations between Taiwan and Japan at a time when the two are seeking closer ties as a way of protecting themselves from an increasingly belligerent China.

China is the only other country still restricting imports from Fukushima Prefecture and nearby Ibaraki, Gunma, Tochigi and Chiba prefectures.

Farmers and fishermen in Fukushima Sunday called for further efforts to convince the public that their food is safe to eat.

“All we can do is to work harder until people understand that our products are safe,” said Masao Koizumi, a rice farmer in Fukushima.

The prefectural government of Fukushima has been conducting radiation checks on all rice produced in the prefecture. Since 2015, all shipments cleared the screening, with radioactive cesium levels below the 100-becquerel-per-kilogram limit set by the central government.

“When people see the inspection readings, they will know that there is no threat of radioactive materials,” Koizumi said.

Tetsu Nozaki, the head of an association representing fishery cooperatives in the prefecture, said, “We are disappointed, but we just need to make sure that we keep communicating the safety of our products.”