Direct flights between China and London's Heathrow Airport contribute 510 million pounds ($722.4 million) a year to the United Kingdom economy and support 14,550 jobs, according to a new report.

Heathrow Airport commissioned Frontier Economics to carry out research into the economic impact of its connections with China, and released the study to coincide with Prime Minister Theresa May's trade mission to Beijing, Shanghai, and Wuhan.

The airport's managers are seeking approval this year for expansion plans that including a new runway and terminal infrastructure. Heathrow hopes the study will show that an expansion, and additional routes and destinations in China, will boost the economy.

"Expansion of Heathrow is a chance to deepen relations between China and the UK," said John Holland-Kaye, Heathrow's chief executive. "Just one extra route could contribute hundreds of jobs and millions to the UK's gross domestic product. As the country prepares to leave the European Union, and China's economy continues to grow exponentially, this is an opportunity the UK cannot afford to miss."

Heathrow secured government backing for a third runway in 2016. Parliament is expected to vote on a National Policy Statement in the first half of this year that will set out the policy framework for Heathrow's final planning submission.

The proposed expansion is opposed by many people in West London, with critics citing additional air and noise pollution. Some people will have to move to make way for the project.

In a statement, the airport said the UK currently misses out on trade and investment opportunities in 14 Chinese cities served by rival airport hubs in Europe that Heathrow does not have the capacity to fly to.

The study estimates that one additional flight a week to each existing connection could generate an extra 16 million pounds annually for the British economy and generate an additional 530 jobs.

There are more than 100 direct flights between China and Heathrow each week. Of these, 55 go to Hong Kong, 22 to Shanghai, 20 to Beijing, 10 to Guangzhou, and two to Qingdao. The study estimate that the Hong Kong routes alone contribute 315 million pounds out of the 510 million total.

The report comes days after Willie Walsh, chief executive of International Airlines Group, which owns British Airways, wrote a letter to the government calling for cheaper long-term visas for Chinese visitors.

"We need a step change on China – we make it hard for Chinese tourists to visit," Walsh said. "The United States charges 119 pounds for a 10-year visa while Britain charges 767 pounds. Making it easier for Chinese businesses and tourists to come to the UK is critical to boosting our economy and enhancing global trading links, especially post-Brexit. We continue to lose out on the new jobs that Chinese investment and affluent tourists bring."