China has rejected Japan's proposal that it join an international verification framework for assessing the results of radiation level monitoring of treated water being released into the sea from the crippled Fukushima nuclear power plant, sources familiar with the bilateral relationship have said.

China is staunchly opposed to the ocean discharge and has banned all seafood imports from Japan since it began in late August, calling the water "nuclear-contaminated." Beijing has also ignored Tokyo's repeated proposals for a science-based dialogue involving experts on the matter, Japanese officials said Tuesday.

Under the framework, participating countries will compare, analyze and evaluate the results of the monitoring carried out by the Japanese government and the International Atomic Energy Agency on seawater off the coast of Fukushima Prefecture.