CARACAS—Venezuela's economy hit a dubious milestone on Thursday: Inflation is now above 50% a year for the first time since the late President Hugo Chávez took power in 1999.

Venezuela's central bank said prices rose 5.1% in October, pushing the 12-month inflation rate to 54.3%—the highest mark since hyperinflation attacked the country in the mid-1990s.

Two factors have triggered the spike in prices. The first is ramped-up public spending from President Nicolás Maduro, Mr. Chávez's successor. The central bank said the country's money supply grew 70% in the past 12 months, much of it to underwrite a big increase in government spending.

At the same time, however, currency controls Mr. Chávez implemented in 2003 have made access to dollars difficult, causing widespread shortages in an economy that depends on imports for roughly 70% of everything it consumes. The central bank's scarcity index, a measure of basic items missing from the market, edged up to 22.4% in October from 21.2% in September, the highest since at least 2009.

It all adds up to more local money chasing fewer goods—a recipe for price increases, economists said.

"These results are by any measure atrocious," said Tamara Herrera, an economist with Caracas-based financial-research firm Síntesis Financiera. She said the government could respond by extending price controls from staples like food to other consumer goods.

For ordinary Venezuelans, inflation has become a feature of everyday life, prompting many to spend their money immediately.

"There's no way of protecting your money, of protecting your savings," said Johan Davila, a 56-year-old unemployed accountant. "You are in big trouble if you don't have a job."

The rate is quite a bit higher than the average inflation rate during the Chávez/Maduro era of 23.6%, according to a presentation Oil Minister Rafael Ramírez made to investors on Thursday.

The inflation rate is "spiraling to worrisome levels," Goldman Sachs economists Mauro Roca and David Reichsfeld said in a note to clients on Thursday. "Unless there is a consistent set of fiscal and monetary policies in place, inflation could continue to spiral out of control."

Mr. Maduro has alleged that the country's mounting economic woes have been caused by a conspiracy by rivals to his leftist government who hoard products in order to drive up prices. Earlier Thursday, Mr. Maduro said 1,000 inspectors had been sent out as part of a recently launched task force to root out businesses that seek inflated profit or hoard products.

"We are not going to accept speculation under any circumstances," said Mr. Maduro, during an appearance televised on state television. "If I have to confiscate an entire warehouse, I will every day beginning now."

The crackdown was part of a host of economic measures the 50-year-old president announced late Wednesday that he said aimed to "stabilize" the economy. The moves included a reorganization of the government's foreign-currency exchange channels, which would be housed in a new centralized agency dubbed the National Center for Exterior Commerce.

Strict controls make dollars available only through government channels in Venezuela. The lack of dollars has resulted in a swoon of the bolívar on the black market, where a dollar fetches nearly 60 bolívares, according to websites that track the rate. That is more than nine times the official peg of 6.3 bolívares per dollar.

The government here made it a crime to even mention the black-market rate, punishable by as many as seven years of prison time. But Mr. Maduro openly presented details on the currency market during his comments Wednesday night, even mentioning the names of underground websites locals use to track the illegal rate.

Calls seeking further comment from government officials weren't immediately answered.

Venezuela, which relies on oil for more than 90% of government income, has gone through boom-and-bust periods many times before, almost always after the price of oil fell. Inflation spiked to 103% in 1996 amid an economic crisis caused by overspending, debt and falling oil prices.

But even with oil prices holding steady at about $100 a barrel, the Venezuelan economy is facing growing strains from years of increasing government intervention.

Mr. Chávez died in March following a nearly two-year battle with cancer. Mr. Maduro was elected a month later in snap elections.