CHINA has detected omicron in a second major port city, deepening concerns of a wider outbreak at Beijing's doorstep and raising the prospect that more foreign businesses might follow Toyota Motor Corp in halting operations along the northeastern coast.

Chinese officials said last Thursday that at least one person has the more transmissible omicron variant in Dalian, a city of seven million, reports Bloomberg.

The patient showed no symptoms but tested positive after returning from college in the nearby city of Tianjin, where at least 137 other cases were traced. A second person in Dalian has also tested positive with the virus, but the variant is unknown.

Dalian joins Tianjin as the second crucial port city with confirmed omicron cases. Their ports are among the twenty largest in the world - processing a combined total of 25 million TEU in 2020 - and serve as major production hubs for foreign companies such as Airbus and Volkswagen.

Amid Covid-induced delays near Beijing and elsewhere, ships are heading for Shanghai, causing growing congestion there and delaying schedules for container ships by about a week, according to freight forwarders. The delays could ripple as far as the US and Europe.

A broader spread of omicron is bad news for China. With just three weeks to go before the winter Olympics are set to begin in Beijing, China has put in place some of the world's toughest measures to stamp out the virus. Officials in Tianjin closed schools, restaurants and entertainment facilities after dozens of people tested positive. Travel has more or less halted.

As the city ramped up mass testing, Toyota suspended operations last week at its joint-venture car making plant in Tianjin, a city of around 13 million. Others may follow suit. Japanese companies including Sony and Panasonic have operations in Dalian.