Social networking giant Facebook has decided to stop funding a campaign that aims to defeat the California Consumer Privacy Act.

The act requires companies to disclose the type of personal data they gather and give people the right to prevent businesses from selling their personal data, CNET reported on Thursday.

"Facebook, Google, and Comcast each have contributed $2,00,000 since February to the Committee to Protect California Jobs that is opposing the act," the report added.

"We took this step in order to focus our efforts on supporting reasonable privacy measures in California," a company spokesman was quoted as saying, who later added that Facebook still found the act "flawed".

The decision came as Facebook CEO Mark Zuckerberg appeared before the US Congress twice in less than 24 hours, apologising for the data breach scandal involving British political consultancy firm Cambridge Analytica.

Alastair Mactaggart, the chief proponent of the proposed initiative, said: "We're gratified that Facebook has dropped its opposition to the California Consumer Privacy Act.

"Now that they have seen the error of their ways, we hope they will work with us proactively to protect the personal information of all Californians and support us publicly and financially."

Stressing that there is an online propaganda "arms race" with Russia and it was important to make sure no one interferes in any more elections including in India, Zuckerberg told Congress that his own personal data was "improperly shared".

Appearing before the US House of Representatives Energy and Commerce Committee on Wednesday -- his second testimony before the US Congress in less than 24 hours -- Zuckerberg told the lawmakers that his own personal data was part of 87 million users' that was "improperly shared" with Cambridge Analytica.

Earlier, during the first five-hour marathon session at US Congress late on Tuesday, the Facebook CEO conveyed his concerns about the upcoming elections globally.