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The White House and the Centers for Disease Control and Prevention are asking Facebook, Google and other tech giants to give them greater access to Americans' smartphone location data in order to help them combat the spread of the coronavirus, according to four people at companies involved in the discussions who are not authorized to speak about them publicly.

Federal health officials say they could use anonymous, aggregated user data collected by the tech companies to map the spread of the virus — a practice known as "syndromic surveillance" — and prevent further infections. They could also use the data to see whether people were practicing "social distancing."

Some sources stressed that the effort would be anonymized and that government would not have access to specific individuals' locations. They noted that users would be required to opt-in to the effort.

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The federal effort, first reported by The Washington Post, will force the tech giants to weigh their commitments to user privacy against their desire to help combat a disease that has cost thousands of human lives and upended the global economy.

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The government officials have held at least two calls in recent days with representatives from the companies, the sources said. Those officials are "very serious" about making this happen, a person at one of the tech companies said.

Similar and more aggressive surveillance practices have already been put to use in China, South Korea and Israel. The moves have set off alarm bells among privacy advocates who fear what the government may do with users' data.

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Facebook already provides health researchers and nongovernmental organizations in some countries with anonymized data to help disease prevention efforts. Laura McGorman, policy lead of Facebook's "Data for Good" program, said a similar effort could be used "to understand and help combat the spread of the virus."

But other sources warned that providing the government with greater access to anonymized location data now could lead to the erosion of individual privacy down the line, especially if the government starts to ask for non-anonymized data.

Representatives from Facebook, Google, Twitter, Apple, Amazon, Microsoft, IBM and Cisco all took part in the call with White House and federal health officials. Spokespeople for the companies declined to comment on the discussions.