A Chinese vendor selling customized national flags has witnessed a surge in business, driven by demand from overseas Chinese students.

The vendor, known as Shengxin on Taobao.com, is based in Shenzhen, South China's Guangdong Province. 

It has 293 orders waiting to be shipped and 12 waiting for payment, according to a screenshot its salesperson showed to the Global Times on Tuesday.

"Orders have obviously surged," said the salesperson.

"The latest batch of orders came from Chinese students studying in Germany," said the vendor's owner, who gave his surname as Wang. He added that some Chinese based in the UK also placed orders.

In response to the ongoing protests in China's Hong Kong, patriotic Chinese students in Germany, the UK and Australia voluntarily rallied against the recent violence in the city.

In London, thousands of overseas Chinese, waving the Chinese national flag and the flag of the Hong Kong Special Administrative Region (HKSAR), while singing the Chinese national anthem along the way from Chinatown to Trafalgar Square, expressed their firm objection to violence and strong support for the HKSAR government and Hong Kong police, according to the Xinhua News Agency.

In Paris, and in the German cities of Berlin, Cologne and Hamburg, overseas Chinese also held peaceful rallies against the violence.

"We sell customized national flags at prices nearly equal to the cost, and we just want to provide our support to the patriotic cause," Wang said.

A Chinese national flag that's 1,440 cm long and 960 cm wide is sold for 35 yuan ($4.96) by the vendor. 

Some Chinese netizens said they want to buy such flags to express their support for the patriotic cause.

Another vendor Qianqihui on Tmall.com said more orders are expected to be placed in September ahead of the 70th anniversary of the founding of the People's Republic of China.

A spokesperson for China's Foreign Ministry said on Monday that the actions of overseas Chinese "are totally understandable and reasonable for Chinese students and other Chinese citizens overseas to express indignation and opposition against words and deeds that attempt to separate China and smear its image."