Vehicle thefts and carjackings have spiked dramatically in 30 major US cities since the start of the pandemic, a new report says.

The Council on Criminal Justice (CCJ) data found motor thefts doubled in eight of the cities surveyed.

The average increase between 2019 and 2022 was 59%.

Vehicle thefts in the US had been plummeting for decades, but took a sharp upward turn at the onset of the pandemic.

The report calls for immediate action from law enforcement to check the rise.

The CCJ analysis released on Thursday found that 37,560 more vehicles were stolen in 2022 than the year before.

The number of carjackings - defined as auto theft or attempted theft by force or threat - rose by 24% in seven cities: Baltimore, Chicago, Denver, Los Angeles, Memphis, Norfolk and San Francisco.

An estimated $7.4bn (£5.9bn) was lost because of vehicle theft in the US in 2020, the FBI found. Other crimes enabled by motor thefts, such as robberies, burglaries, and drive-by shootings, add to the overall costs.

Carjackings are most likely to occur at or near the victim's home, according to the report, and nearly 40% of carjackers are armed with a firearm.

"The nature of this offence, and the increase in public anxiety that it has caused during the pandemic, have made it emblematic of contemporary urban crime," says the report.

Data from Chicago suggests that most offenders there are young adults. However, the share of carjackings by juveniles more than doubled there, from 18% to 41%, between 2016 and 2021.

One hypothesis cited by the report for the recent spike in thefts was that during the pandemic, as unemployment rose, people left their cars unattended at home instead of in secure parking facilities at work. But the report did not find it conclusive.

"Why did motor vehicle thefts continue to increase even after people began to return to work? And why did vehicle thefts begin to rise in 2022, well after the conditions of everyday life had returned to something like normal?" the report's authors questioned.

Carjackings since the pandemic have also been on the rise in Canada, local police have said. During one case last year in Toronto, police arrested 16 people, laid 116 charges and recovered over C$1.4m ($1m; £846,000) worth of stolen vehicles.