Oil prices have risen above $100 ($143) a barrel as global trade resumed this morning, reaching their highest level in almost four years.

In a development that will add almost 20 cents to a liter of gasoline if it continues, West Texas crude jumped from $91 a barrel to $108 a barrel, an increase of more than 18 percent in just a few minutes.

The last time oil was above $100 a barrel was in mid-2022, after the Russian invasion of Ukraine. In the early stages of that war, oil peaked at $115 a barrel.

But with fears growing about the effective closure of the Strait of Hormuz, through which about 20 percent of the world’s oil is shipped, investors fear oil will have to rise even higher.

AMP chief economist Shane Oliver, who predicted oil would break the $100 mark, said high-priced crude would not only increase inflation but also slow the global and Australian economies.

He said it was a concern for the Reserve Bank that if inflation rose, workers and businesses might try to protect themselves by raising wages and retail prices.

“That’s why he’s worried about inflation expectations, that households might get used to higher inflation, which would mean pressure to raise wages while companies might think they can increase margins,” he said.

The rise in oil has also affected the Australian dollar, which is now trading below 70 cents, having lost around 0.4 cents in the last hour.