US Secretary of State Mike Pompeo on Monday warned Silicon Valley not to bolster China's "Orwellian" state, two days before the world's two largest economies sign a partial trade deal.

Speaking to a tech-heavy crowd in San Francisco, Pompeo trumpeted the "phase one" deal to tame a two-year trade war but told businesses that they needed to do more.

"We need to make sure American technology doesn't power a truly Orwellian surveillance state. We need to make sure American principles aren't sacrificed for prosperity," Pompeo said at the Commonwealth Club.

He said he was not discouraging firms from heading to China, insisting that the Trump administration wants "American companies to get rich doing business there."

"At the same time, we need to make sure that our companies don't do deals that strengthen our competitor's military or tighten their regime's grip of repression in parts of that country," he said.

Rights advocates have voiced growing concern about China's use of technology to develop intrusive electronic surveillance.

"Ask yourselves just a few questions -- who am I dealing with? What's the true risk/return calculus to doing business in China?" Pompeo said.

Trump is set to sign the partial deal on Wednesday after prolonged feuding, dropping new tariffs that were set to take effect on Chinese electronic products and cutting in half those imposed on September 1 on $120 billion worth of products.

The White House has said the agreement includes improvements on Beijing's requirements that foreign companies transfer technology -- which the United States say is a pretext for rampant intellectual theft.

The Trump administration says that the accord will also give US companies better access to the Chinese market for financial services and require China to buy more US products.

"We will do our part in the government. We will keep ramping up our enforcement," Pompeo said.

"But defending freedom and national security isn't just the government's job. It's one for each and every citizen," he told the tech companies.