More than a thousand Google employees have signed a letter protesting against the company’s secretive plan to build a search engine that would comply with Chinese censorship.

The letter calls on executives to review ethics and transparency at the company.

The letter’s contents were confirmed by a Google employee who helped organise it but who requested anonymity.

The letter says employees lack the information required “to make ethically informed decisions about our work” and complains that most employees only found out about the project — nicknamed Dragonfly — through media reports.

The letter is similar to one thousands of employees had signed to protest against Project Maven, a US military contract that Google decided in June not to renew.