SINGAPORE—Exports from Singapore’s bellwether economy slumped to near their weakest level since the global financial crisis eight years ago, the city state said on Monday, illustrating new pressures on Asia’s export-dependent economies.

The trend has worrying implications for the state of the global economy, which has been roiled this year by market volatility spilling out from China and the slide in the prices of oil and other commodities. Singapore’s small, export-dependent economy is seen as a proxy for the broader state of Asian trade.

Singapore’s non-oil domestic exports fell 9.9% in January from a year earlier, official statistics show, as shipments to China, its largest trading partner, contracted at a faster pace. The data reflects the slowest pace of economic expansion in China for 25 years, as Beijing pursues a bumpy shift from investment to consumption-led growth.

South Korea, which sends a quarter of its exports to China, said this month that exports fell 18.8% in January, their biggest fall since August 2009. Indonesia said exports contracted 20.7% last month. Even India, which has strong domestic demand, said exports fell in January for the 14th straight month, down 13.6%. All were compared with the same month a year earlier.

China, a voracious consumer on which many Asian economies depend, said exports in January fell 11.2% from the year earlier period, more than expected. Chinese imports, more than half of which are supplied by other Asian countries, fell 18.8%, more than four times faster than forecast by economists.

“Whatever data is available right now, it’s looking bad,” said Taimur Baig, an economist at Deutsche Bank in Singapore. “It’s been a worse-than-trend outcome for every country that has reported January data.”

Many economists point to several reasons for slowing trade flows.

What began more than a year ago as a slowdown in commodities exports has spread to other traded goods as falling global growth hurts consumer and corporate spending even in countries, like India, that are less reliant on commodities. The International Monetary Fund last month downgraded its outlook for world economic growth by 0.2 percentage point to 3.4%.

Further, economists say whatever a tepid economic recovery is happening in the U.S. and Europe is being driven more by their domestic consumption of services than by demand for goods from Asia.

In Asia, too, domestic demand has gradually become a more important factor in growth as governments look to rebalance their economies away from reliance on exports, said Frederic Neumann, co-head of Asian economics research at HSBC in Hong Kong.

“The real problem here is that because domestic demand is turning down, suddenly export malaise is becoming even more of a problem,” Mr. Neumann said.

Finally, many countries seeking to protect jobs and local industries appear to have sought to restrict trade rather than promote it. Mr. Baig counted about 800 new trade restrictions in the world’s 20 largest economies since the financial crisis.

Some Asian countries, including Indonesia and Thailand, have tried to boost growth through infrastructure spending. Late last year, South Korea reported its fastest quarterly growth in five years thanks to a stimulus-driven rebound in domestic demand.

But most in the region are still heavily exposed to global trade and as the effect of stimulus measures wears off growth is likely to slow again, some economists say. These people say that structural problems in Asian economies such as high debt, inefficient state enterprises and regulation are the biggest inhibitors to domestically-driven growth.

Singapore has responded by attempting to refocus its economy on added-value industries such as research and development and less on its traditional re-export model.

As for other countries in the region, economists are expecting more monetary easing from central banks as a way to shore up growth rates and encourage spending, in contrast with the U.S. Federal Reserve, which raised interest rates in December. Taiwan, South Korea, Thailand, Indonesia, India and China are all expected to loosen monetary policy, according to Credit Suisse.

The sluggish export numbers seen in January across Asia are “more about end demand in China” than about U.S.-driven growth, “which is why we continue to expect Asian central banks to diverge from the Fed,” said Michael Wan, economist as Credit Suisse in Singapore. Mr. Wan, like many other economists, expect a very slow pace of interest rate increases in the U.S.