Internet giant Yahoo says it is "deeply concerned" over government efforts to impose censorship.
Activists have attacked Yahoo's actions
The firm has been pilloried over accusations it has provided information to the Chinese government that led to the jailing of two dissidents.
Ahead of a US Congress hearing on Wednesday to discuss the issue, Yahoo said firms could promote openness.
In a written statement that did not refer to China, it said it was committed to an unrestricted internet.
The Chinese government enforces strict laws on internet use, blocking content it considers a threat, including references to the Tiananmen Square massacre and notable dissidents.
Yahoo has been accused of releasing data that led to the jailing of online writer and corruption critic Li Zhi for eight years in 2003, and to the imprisonment of reporter Shi Tao in a separate case.
The firm said that "knowledge was power" and that firms could be a part of a wider effort to promote a free internet.
"We are deeply concerned by efforts of governments to restrict and control open access to information and communication.
"We also firmly believe the continued presence and engagement of companies like Yahoo is a powerful force in promoting openness and reform.
"If we are required to restrict search results, we will strive to achieve maximum transparency to the user."
The firm said companies could not be expected to take a stand on their own.
"Private industry alone cannot effectively influence foreign government policies on issues like the free exchange of ideas, maximum access to information, and human rights reform, and we believe continued government-to-government dialogue is vital to achieve progress on these complex political issues.
"We will work with industry, government, academia and NGOs (non-government organisations) to explore policies to guide industry practices in countries where content is treated more restrictively than in the United States and to promote the principles of freedom of speech and expression."
Microsoft, Google, and Cisco have all been accused of helping China restrict access to the internet.
Yahoo and other firms have defended their positions, saying they have only complied with local laws.