Thousands of people flocked to a zoo in Japan on Sunday to say farewell to the country's last two giant pandas, who are set to return to China on Tuesday.

Emotions ran high at the Ueno zoo in Tokyo as people stood in line – some for as long as three-and-a-half hours – to see twin cubs Xiao Xiao and Lei Lei one last time.

This comes at a very tense moment in relations between Tokyo and Beijing. Ties have sharply deteriorated after Japanese Prime Minister Sanae Takaichi said Tokyo would get involved militarily if China attacked Taiwan.

The twins' departure will leave Japan without any pandas for the first time since 1972, the year the two countries normalised diplomatic ties.

The People's Republic of China has used giant pandas as a gesture of goodwill towards its international allies and competitors since its founding in 1949.

But China retains ownership of all pandas it loans to foreign countries, including cubs born abroad. In return, host countries pay an annual fee of about $1m (£790,000) per pair of pandas.

According to Tokyo's metropolitan government, some 108,000 people vied for one of the 4,400 slots for a last look at the zoo's beloved pandas.

"I have been bringing my son here since he was a baby, so I hope it becomes a good memory for him. I'm glad we could come today to remember them," one woman told the BBC.

Another woman recalled witnessing the pandas' growth journey. "Witnessing their growth, especially since they were so small, has been such a joy," she said.

Some visitors were pictured sobbing as they bade the bears goodbye.

Xiao Xiao and Lei Lei were born in 2021 at the Ueno zoo to their mother, Shin Shin, and their father, Ri Ri, both of whom were on loan to Japan for breeding research.

More recently, China's panda loans have coincided with major trade agreements. In 2011, the loan of two pandas to Edinburgh Zoo in Scotland was agreed during negotiations over contracts to supply salmon meat, Land Rover vehicles and energy technology to China.

Many pandas have been returned to China in recent years – a loan agreement typically lasts 10 years, although extensions are common.

However, the prospects of a new panda loan to Japan have remained uncertain amid the escalating row.

Japanese Prime Minister Sanae Takaichi's comments on Taiwan angered Beijing, which views the self-governed island as part of its territory and has not ruled out the use of force to "reunite" with it.

Both sides have since engaged in increasingly hostile actions and rhetoric. Early this month, China tightened restrictions on exports of rare earth-related products to Japan.