United States Senators Ted Cruz and Patrick Leahy this week sent a letter to Apple CEO Tim Cook demanding answers after the iPhone maker removed a number of privacy-providing apps from its Chinese App Store.

In the letter, the senators said China had an "abysmal" human rights record with respect to freedom of expression and free access to information online and offline.

Cruz and Leahy wrote they were concerned that Apple "may be enabling the Chinese government's censorship and surveillance of the Internet."

Apple declined to comment specifically on the letter.

In July, Apple pulled several virtual private network (VPN) apps from the Chinese version of its App Store. Some of the affected VPN providers received notification from the iPhone maker that their apps were removed for including "content that is illegal" in the mainland.

VPNs allow users in China bypass the country's infamous "Great Firewall" that heavily restricts access to foreign websites. Those apps also allow for privacy by hiding browsing activities from internet service providers.

Cook, during an earnings call, addressed the decision to remove those apps. He said that while Apple would "obviously rather not remove the apps," it will follow the law in whichever country it does business.

"We believe in engaging with governments even when we disagree. This particular case, we're hopeful that over time the restrictions we're seeing are lessened, because innovation really requires freedom to collaborate and communicate," Cook previously said.

The senators noted that Cook was awarded the free speech award at Newseum's 2017 Free Expression Awards, where he said, according to the letter, "First we defend, we work to defend these freedoms by enabling people around the world to speak up. And second, we do it by speaking up ourselves."

Cruz and Leahy said the removal of VPN apps "that allow individuals in China to evade the Great Firewall and access the Internet privately does not enable people in China to 'speak up.'"

In a detailed list of questions, the senators asked Cook to explain if Apple had raised concerns when Beijing was formulating its cybersecurity laws or if the tech giant pushed back when asked to take down several of the apps.

They also asked if Apple had preemptively taken down any apps from the China App Store and whether it had either promoted freedom of speech in the country or condemned the "government's censorship and surveillance mechanisms."

In January, China's Ministry of Industry and Information Technology embarked on a campaign to "clean up" the country's internet connections by March 31, 2018. The ministry said that, while China's internet access service market was facing a rare opportunity for development, there were also signs of disorderly development that needed to be fixed.

Since then, the Chinese government had undertaken several initiatives that have tightened control of the internet inside the country and have reduced online anonymity.

To be sure, Apple's removal of those apps was not the first time Beijing's cyber regulators had gone after VPN providers.

Read the full letter from Senators Ted Cruz and Patrick Leahy here.