A senior nuclear adviser to Japanese Prime Minister Naoto Kan on Friday submitted his resignation, saying the government had ignored his advice and failed to follow the law.
Toshiso Kosako, a Tokyo University professor who was named last month as an advisor to Kan, said the government had only taken ad hoc measures to contain the crisis at the crippled Fukushima nuclear power plant.
In a tearful press conference, he said the government and its commissions had taken "flexible approaches" to existing laws and regulations, and ignored his advice after he was named an advisor on March 16.
"I cannot help but to think (the prime minister's office and other agencies) are only taking stopgap measures... and delaying the end" of the nuclear crisis, he told reporters.
Tokyo officials had drafted measures to deal with the accident that were not in strict accordance with the law, and the decision-making process had been unclear, he said.
"There is no point for me to be here," as the Kan administration had failed to listen to him, said Kosako, an expert on radiation safety.
It was not clear whether the government would accept the resignation, but his letter and comments served as a fresh blow to the embattled Kan, who has been badly criticised for his handling of the nuclear crisis.
The Fukushima Daiichi power plant has been releasing radioactive materials since it was battered by a magnitude-9.0 earthquake and tsunami on March 11 that left nearly 26,000 people killed or missing.
The nuclear accident and natural disaster have forced the evacuation of more than 150,000 people from their homes.