BEIJING (AP) — More than a dozen human rights groups have sent a letter to Google urging the company not to offer censored internet search in China, amid reports it is planning to again provide the service in the giant market.

The joint letter dated Tuesday calls on CEO Sundar Pichai to explain what Google is doing to safeguard users from the Chinese government's censorship and surveillance.

It describes the censored search engine service, codenamed "Dragonfly," as representing "an alarming capitulation by Google on human rights."

"The Chinese government extensively violates the rights to freedom of expression and privacy; by accommodating the Chinese authorities' repression of dissent, Google would be actively participating in those violations for millions of internet users in China," the letter says.

In a statement, Google said it has "been investing for many years to help Chinese users, from developing Android, through mobile apps such as Google Translate and Files Go, and our developer tools. But our work on search has been exploratory, and we are not close to launching a search product in China."

The expression of concern by the rights groups follows a letter earlier this month signed by more than a thousand Google employees protesting the company's secretive plan to build a search engine that would comply with Chinese censorship. The letter called on executives to review ethics and transparency at the company.

Google had previously complied with censorship controls starting in 2006 as it sought a toehold in the booming Chinese economy. But it exited the Chinese search market in 2010 under unrelenting pressure from human rights groups and some shareholders to leave.

The letter, signed by groups including Amnesty International, Human Rights Watch and Reporters Without Borders, said China's controls over the internet have only strengthened since then amid an overall crackdown on civil liberties and freedom of expression.

"It is difficult to see how Google would currently be able to relaunch a search engine service in China in a way that would be compatible with the company's human rights responsibilities under international standards, or its own commitments," the letter said.

According to online news site The Intercept, Google created a custom Android app that will automatically filter out sites blocked by China's so-called "Great Firewall."

Google co-founder Sergey Brin was born in the Soviet Union in 1973 and lived there until age 6 when his family fled. He has said his experience with a repressive regime shaped his and the company's views.

However, Pichai, who became CEO in 2015 when Google became part of parent Alphabet, has said he wants Google to be in China serving Chinese users.

In December, Google announced it was opening an artificial intelligence lab in Beijing, and in June, Google invested $550 million in JD.com, a Chinese e-commerce platform that is second only to Alibaba in the country. The companies said they would collaborate on retail solutions around the world without mentioning China, where Google services including Gmail and YouTube are blocked.