Asian companies are being warned not to underestimate their exposure to the Ukraine crisis as the Russians have invested in quite a lot of their bonds, and it is estimated that Russian authorities own a combined US$140 billion (HK1.1 trillion) of Chinese bonds, while the Kremlin has now banned coupon payments to foreigners.

Managements should review existing customers and partners to determine if they pose a serious threat, as many countries are excluding Russian companies from international payment systems due to sanctions, said Steve Vickers, chief executive at risk advisory firm Steve Vickers and Associates.

This came as Australia & New Zealand Banking Group said the Bank of Russia could hold US$80 billion of yuan debt, while the National Wealth Fund is estimated to own US$60 billion. Together, that represents almost a quarter of foreign ownership in China's domestic bond market, it said.

"Russia's China bond holdings and CNY could be major foreign assets and currency that Russia can access," its analysts said. "We are watching if Russia will liquidate the assets if CNY cash is needed to meet other payment obligations."

Meanwhile, Russia's transport and logistics company Fesco Transportation said it accepts yuan from customers, as businesses struggle to cope with international sanctions over Russia's invasion of Ukraine.

It said in a statement that it was also offering customers "various alternative options of payment" for euro and US-dollar transactions involving sanctioned lenders, including through other banks.

At the same time, Chinese traders are scaling back imports of Russian coal as they struggle to secure financing from state banks worried about potential sanctions after Russia invaded Ukraine, in early signs of supply disruption from the world's third-largest coal seller.

And the Russian central bank has banned coupon payments to foreign owners of US$29 billion ruble bonds known as OFZs, in what it called a temporary step to shore up markets in the wake of international sanctions.

Separately, Apple halted product sales in Russia. Google said on Tuesday that it has blocked mobile apps connected to RT and Sputnik from its Play store, in line with an earlier move to remove Russian state publishers from its news-related features.

Exxon Mobil also said it would exit Russia oil and gas operations that it has valued at more than US$4 billion, and halt new investment.

The ruble has taken a battering. AFP

Russian invasion a threat to China markets