By Casey Hall and Albee Zhang

BEIJING (Reuters) -Chinese consumers stayed away from sea food stalls and rushed to stock up on salt following Beijing's condemnation of Japan's release on Thursday of treated radioactive water into the Pacific Ocean from the wrecked Fukushima nuclear plant.

During the past few weeks, China's state media and government officials repeatedly criticised the plan, saying the Japanese government had not proved that the water discharged would be safe, emphasising its danger to neighbouring countries.

Hours after Japan went ahead with the release, China issued a blanket ban on all aquatic products from Japan.

At the Jiangyang Seafood Market in Shanghai's Baoshan District, two vendors said that the market's management toured stalls on Thursday afternoon and requested the removal of Japanese products.

Though Japanese seafood was no longer on sale, some vendors voiced concerns that customers would be put off all seafood, regardless of origin.

"I think it will influence people eating seafood a little, even if it's not from Japan, there's nothing we can do about that," said a vendor surnamed Wang, who declined to give his first name for privacy reasons.

Prior to Thursday's action by Japan "we had a lot of people coming here every day," said Chen Yongyao, an employee at a frozen seafood store in Jiangyang.

Now, he said "it's not busy at all, no one is buying."

The scare has also impacted demand for salt.

The state-run National Salt Industry Group, the world's biggest common salt maker, urged people not to panic buy in a statement issued late of Thursday, reassuring consumers that it was ramping up production and the shortfall would be temporary.

Supermarket shelves were emptied of salt and online sales platforms were sold out in some places, including Beijing and Shanghai, as people rushed to stock up.

According to an data published by Chinese media outlet Jiemian, 6.73 million orders for salt were placed on the e-commerce platform JD.com since Aug.22.

Salt was also a hot commodity in China in 2011 following the initial Fukushima nuclear disaster. Aside from the concerns about the potential contamination of sea salt, there is also widespread belief in China that iodised salt can help protect against radiation poisoning.

Shanghai shopper Wang Kaiyun, 56, said she knew many people who believed salt protects against radiation poisoning, but she was in the supermarket to stock up before it ran out.

"I saw all of the videos online showing no salt in the supermarkets," she said. "I thought I should buy it now in case I need salt for cooking in the near future."

Japan has criticised China for spreading "scientifically unfounded claims" and maintains the water release is safe, noting that the International Atomic Energy Agency (IAEA) has also concluded that the impact it would have on people and the environment was "negligible."

(Reporting by Casey Hall, Xihao Jiang, Albee Zhang and Brenda Goh; Editing by Simon Cameron-Moore)