Germany, Belgium and Luxembourg on Saturday discouraged non-essential trips to China, the world's most populous nation, as it struggles with a surge in Covid cases after relaxing strict virus restrictions.

"We currently discourage non-essential trips to China. The reason is a peak in Covid infections and an overwhelmed health system," the German foreign ministry said on Twitter.

Neighbouring Belgium and Luxembourg were swift to follow suit.

"Luxembourg is aligning itself with the German travel advisory and is currently advising against non-essential travel to China," the country's foreign ministry said in a statement.

Belgium's foreign ministry said on its website that "since December, China has been experiencing its biggest wave of infections due to the end of the zero-Covid policy".

"In view of the risk of hospital overcrowding and, consequently, the risk of not being able to be treated quickly in the event of an emergency, non-essential travel is not recommended for the time being."

More than a dozen countries have imposed new travel regulations on travellers from China.

European Union experts this past week "strongly encouraged" the bloc's 27 member states to demand Covid tests before departure for people on flights from China, and conduct random tests upon arrival.

Several EU nations -- including Germany, France, Italy and Spain -- have already announced Covid test requirements on travellers coming from the Asian nation.

The United States and Japan are among the non-European countries to have brought in similar measures.

Chinese authorities have recently said the first wave of infections has hit a peak in cities including Beijing and Tianjin.

But the end is far from near, with officials warning of a multi-pronged outbreak in the coming weeks as city workers return to rural hometowns during the winter travel season.

Despite a rebound in infections, Chinese authorities will end mandatory quarantines on arrival in China starting Sunday and allow Chinese people to travel abroad again after three years of restrictions.

On Tuesday, Beijing condemned the imposition of Covid tests by some countries as "unacceptable" and threatened "countermeasures".