All products by Qihu 360, a Chinese security software company, was removed from Apple’s app store on Monday, which may be the most severe reaction from Apple, Qianjiang Evening News reported.

Apple did not explain why they removed Qihu 360’s applications except to say that the software may not be compatible with the Apple iSO system.

Qihu 360 said in a public letter that there is no problem with the quality of its products. The company said that it is now talking with Apple about the issue.

A staff member from Qihu 360 also said the company is planning to launch a lawsuit against Jinshan, a competitor, for allegedly spreading rumors about Qihu 360’s use of customer information that led to the removal of its products, the paper said.