US presidential hopefuls Kamala Harris and Donald Trump clashed on China and economic issues Tuesday, with the Democratic candidate saying he "sold us out" on China while the former president declared "they've destroyed the economy."

"He ended up selling American chips to China to help them improve and modernize their military," said Harris in her first debate with Trump ahead of the November 5 election.

"(He) basically sold us out when a policy about China should be in making sure the United States of America wins the competition for the 21st century," she added.

Harris's comments came as she and Trump crossed swords on various economic issues including the cost of living, inflation and her position on fracking.

"He invited trade wars," Harris said, referring to a tit-for-tat escalation of tariffs between the United States and China during Trump's 2017-2021 presidency.

With Trump proposing across-the-board tariffs of 10 percent to 20 percent on all imports if reelected, Harris likened the plans to a "sales tax" -- given concerns that costs could be passed on to consumers.

Trump is looking to impose a higher level of levies on imports from China, at 60 percent.

Harris also took aim at Trump on Tuesday for thanking Chinese President Xi Jinping in 2020 for his country's handling of Covid-19, saying this was despite a lack of "transparency" about the virus's origins.

Fracking, inflation

Republican candidate Trump, in turn, claimed that Harris "has no policy" and said that the Biden-Harris administration has kept his administration's tariffs on China in place.

The Biden administration this year intensified US tariffs on Chinese goods ranging from electric vehicles to semiconductors.

Trump also honed in on the issue of fracking, a sensitive issue in battleground Pennsylvania -- a key energy state -- saying Harris "will never allow fracking" there.

"If she won the election, fracking in Pennsylvania will end on day one," he added, in a nod to 2019 comments that she would ban it.

Harris maintained she had made it clear in 2020 that she would not enact a fracking ban, and has not supported doing so as vice president. 

Trump also accused the current administration of ruining the economy, citing high inflation in recent years.

The economy remains the most important issue for likely voters this November, according to a September New York Times/Siena poll.

Inflation surged after the Covid-19 pandemic, with supply chain problems causing prices to rise while stimulus from the US government added to demand.

Price increases have since slowed and are close to policymakers' target levels.

Harris said that Trump "left us the worst unemployment since the Great Depression."

"What we have done is clean up Donald Trump's mess," she said.