The US, which closed its borders to much of the world as the pandemic took hold, has said it plans eventually to begin allowing fully vaccinated foreigners back in, while China has tightened overseas travel curbs amid surging infection numbers, reports AFP.

The two countries' travel-related moves come as the fast-spreading Delta variant cuts a deadly swath across the planet, not only affecting movement between countries but also the northern hemisphere's summer tourist season.

Recognising the importance of international travel, a White House official said in a statement that the US wants to reopen to visitors from abroad in a “safe and sustainable manner,” though without specifying a timeframe.

Meanwhile, China's immigration authority has announced it will stop issuing ordinary passports and other documents needed for exiting the country in “non-essential and non-emergency” cases. However, the authorities have pulled back from issuing a blanket ban on overseas travel.