China reported 46 new coronavirus infections on Sunday, including its first case of local transmission in four days.

While the number of virus cases has been falling over the past few weeks in China, there has been growing concern around imported cases as countries around the world step up their fight against the pandemic.

An estimated 900 million people in 35 countries are now confined to their homes, including 600 million cooped in due to government lockdown orders, according to an AFP tally.

While about 56 million people in China's central Hubei province had been locked down since late January, authorities have begun to ease travel restrictions as the number of fresh infections in Hubei dropped to zero.

On Sunday, China reported 46 new virus cases, with all but one brought in from other countries. For the three consecutive days before, it had no new local cases.

The new domestic infection came about in Guangdong province, and was linked to a previous imported case, according to local authorities.

This is the highest number of new infections from abroad that China has seen in recent days, bringing the tally of imported cases to 314.

China has been stepping up measures to deal with cases from overseas, with Beijing and other regions forcing international arrivals to go into a 14-day quarantine. The civil aviation ministry also said it would limit passenger numbers on inbound international flights.

The death toll from the virus has spiked to over 12,700 worldwide, with the crisis shifting from Asia to Europe -- which now accounts for more than half the world's fatalities linked to COVID-19.

Italy, which reported nearly 800 deaths on Saturday alone, has been the worst-hit.