More than 240 Google employees have signed an open letter calling on the company to abandon its plan for a censored search engine in China, as protesters took to the streets in eight cities to condemn the secretive project.

The letter was published Tuesday morning, signed by a group of 11 Google engineers, managers, and researchers. By early evening, a further 230 employees had added their names to the letter in an extraordinary public display of anger and frustration with Google’s management over the censored search plan, known as Dragonfly.

The search engine was designed by Google to censor phrases about human rights, democracy, religion, and peaceful protest, in accordance with strict censorship rules enforced by China’s authoritarian government. The search platform would link Chinese users’ search records to their cellphone numbers and share people’s search histories with a Chinese partner company — meaning that Chinese security agencies, which routinely target activists and critics, could obtain the data.

The Google employees said on Tuesday that they believed the company was no longer “willing to place its values above its profits.” They wrote that the Chinese search engine would “make Google complicit in oppression and human rights abuses” and “enable censorship and government-directed disinformation.” They added:

Our opposition to Dragonfly is not about China: we object to technologies that aid the powerful in oppressing the vulnerable, wherever they may be. The Chinese government certainly isn’t alone in its readiness to stifle freedom of expression, and to use surveillance to repress dissent. Dragonfly in China would establish a dangerous precedent at a volatile political moment, one that would make it harder for Google to deny other countries similar concessions.

In August, 1,400 Google employees protested Dragonfly privately, with many anonymously signing a letter that was circulated inside the company. Organizers of the protests have until now sought to keep their discontent in-house, feeling that negotiating with management away from the media would be the best way to address their concerns, sources said.

But the organizers have become increasingly dissatisfied with company executives who have refused to answer questions about Dragonfly and engage on human rights issues. That is one of the principal reasons why the employees decided on Tuesday to go public with a new letter, which was not signed anonymously, in what amounted to an unprecedented rebuke to company bosses.