International environmental organization Greenpeace Tuesday released the results of its latest investigation, which found some Lipton tea bags contained high levels of toxic pesticides.

Greenpeace randomly bought four different tea products made by Lipton - black tea, green tea, jasmine tea and "Iron Buddha" oolong (Tieguanyin) in March and sent them to an accredited laboratory for independent testing.

According to the report, there were up to 13 types of pesticide residues on the green tea and Tieguanyin and nine types on the jasmine tea.

"All these pesticides are shown to likely affect male fertility and the health of unborn fetuses," said the report.

Some of the pesticides found on the Lipton green tea, jasmine tea and Tieguanyin are banned for use on tea trees by the Ministry of Agriculture (MOA), including methomyl and endosulfan, said the report.

"This contradicts Lipton's promise of only using pesticides approved by the MOA," Wang Jing, a food and agriculture campaigner from Greenpeace, told the Global Times.

Unilever, manufacturer of Lipton tea, made an announcement on its official Sina microblog Tuesday saying that their tea products are safe and completely comply with all the relevant regulations on pesticide residues in China.

"The contents of the black tea involved in the investigation are imported from overseas and both the contents and finished products of the green tea, Tieguanyin and jasmine tea are regularly sent to trustworthy third-party institutions for inspection," said Unilever.

Unilever also said that they have contacted Greenpeace to discuss its inspection methods and results.

Lin Yan, a researcher with the Beijing Pesticide Association, told the Global Times that given the bio-pesticide's slower effect, some tea planters opt to use toxic pesticides that are cheaper and more effective.

"The best way to have safe tea is to ensure that tea planters do not use those forbidden pesticides," Lin told the Global Times.

This is the second time Lipton tea products are involved in a safety scandal. Late last year, a batch of Lipton tea produced and sold in China was removed from shelves after the country's food safety watchdog found it contained excessive levels of toxic rare earths.

China has established and amended 2,319 standards on the limitation of pesticide residues over the past two years. A quality standard system and a risk assessment system are also set up for agricultural products, said Chen Xiaohua, vice-minister of agriculture, at a conference held in Shanghai on Monday.