Chinese chives tainted with pesticide reportedly sickened nine people who ate at a fast food restaurant in Qingdao, East China's Shandong Province starting on April 1.

The Qingdao Administrative Bureau of Industry and Commerce investigated and found that the questionable Chinese chives were purchased at a vegetable market that buys them from Gaomi and Shouguang near Qingdao.

The city's health authority shut down the restaurant last week, Wuhan Evening News reported Sunday, after the food poisoning cases were reported.

The nine customers approached the bureau last week to ask for financial compensation after they recovered from food poisoning last Saturday, the newspaper reported.

Up to 1,950 kilograms of pesticide-tainted Chinese chives were destroyed by Saturday under the supervision of officials. And every box of Chinese chives sold in Qingdao is required to pass a pesticide test before they are allowed into the market.

China National Radio reported Sunday that Qingdao has banned the chives from Xiazhuang, Heya township and Daotian township in Shouguang.

The incident has posed some challenges for local Chinese chive farmers since more restricted regulations are being carried out on vegetables sold at markets.

A village director surnamed Dong told the Global Times Sunday that Qingdao administrative bureau took some chive sample from Sunshou for pesticide residue tests and promised to let the products enter Qingdao if the results are negative.

The average price of Chinese chives was 4 yuan ($0.58) per kilogram before the incident happened and it fell to 2 yuan ($0.29) per kilogram, villagers told the Global Times Sunday.

Other provinces have been checking chives more carefully after the incident.

A manager at Beijing Xinfadi agricultural products wholesale market told the Beijing Evening News on Saturday that no pesticide-tainted products were found.

Major wholesale vegetable markets in Nanjing and Yangzhou in East China's Jiangsu Province and Guangzhou in Guangdong Province said no pesticide tainted Chinese chives from Shandong was founded in local markets.

A waitress at a Sichuan style restaurant in Beijing told the Global Times Sunday that Chinese chives and fried eggs was still a popular menu item.

Yao Shouqin, a Qingdao resident, told the Global Times that his friends know about the chive problem and were planning to be more cautious.

"Problematic vegetables in open markets may not be a surprise. But the quality of Chinese chives sold in big supermarket are still reliable," said Yao.