* HK protesters target mainland Chinese visitors for first time
* Latest protest follows ransacking of legislative building
* Protesters want to explain their opposition to extradition bill
* Security tightened around train stations, popular shopping area (Adds detail about stand-off with police, paragraphs 20-21)
By Felix Tam and Farah Master
HONG KONG, July 7 (Reuters) - Tens of thousands of protesters marched through one of Hong Kong's most popular tourist areas on Sunday, trying to gain support from mainland Chinese visitors for the city's opposition to an extradition bill which has caused political turmoil.
Protests against the now-suspended bill have drawn millions of people to the streets in the former British colony in recent weeks, posing the biggest challenge Beijing has faced to its rule in the territory since Hong Kong returned to Chinese control in 1997.
The protests have received little coverage in mainland China, however, with censors blocking news of the largest demonstrations on Chinese soil since the bloody suppression of pro-democracy protests centred on Beijing's Tiananmen Square in 1989.
The bill, which would allow people to be sent to mainland China for trial in courts controlled by the Communist Party, has triggered outrage across broad sections of Hong Kong society amid concerns it threatens the much-cherished rule of law that underpins the city's international financial status.
Hong Kong has been governed under a "one country, two systems" formula since its return to Chinese rule, allowing freedoms not enjoyed in mainland China, including the right to protest and an independent judiciary.
China and Britain have engaged in a public spat over the bill but Chinese ambassador Liu Xiaoming told BBC TV on Sunday that China was "not interested in diplomatic war with the UK" and he had full confidence in Hong Kong's ability to resolve the situation without China's intervention.
Protesters on Sunday braved intermittent rain and marched through streets of Tsim Sha Tsui, a popular shopping destination dotted with luxury shops, to try to deliver their message directly to mainland Chinese tourists in the hope of garnering sympathy.
At times they shouted slogans in Mandarin, mainland China's official tongue, as opposed to Hong Kong's main language Cantonese.
They also handed out flyers and sent messages by social media and Apple's phone-to-phone AirDrop system written in the simplified form of Chinese characters used on the mainland.
The short march finished at the city's high-speed rail station that connects Hong Kong to the mainland, one of the main entry points for Chinese visitors but a sensitive spot after part of the facility came under Chinese jurisdiction last year.
"It is hoped that Hong Kong people can spread how Hong Kong people can march peacefully and bring the protest information back to the mainland to mainland visitors," Lau Wing-hong, one of the protest organisers, told Reuters.
The march was the first major demonstration since Monday when protesters besieged and ransacked the legislative building in the heart of the city on the 22nd anniversary of the handover before being driven back by police firing tear gas.
The authorities took no chances. Police and train staff guarded every exit of the station. Hong Kong's MTR Corp Ltd , which runs the city's metro, planned to shut all entrances to the West Kowloon station apart from a route for passengers. Food and beverage outlets were also closed.
Online train tickets between Hong Kong and Shenzhen on the mainland were displayed as sold out from 2:30 p.m.-6:30 p.m. (0630 GMT-1030 GMT), coinciding with the hours of the protest.
Shanghai businessman Alan Zhang watched the procession near an Apple store on Canton Road.
"Actually, I feel quite touched to see how Hong Kong people fight for their freedom," said Zhang, 54, a frequent visitor to Hong Kong.
"That's something we can't do in China. I think first-time travellers do not know what is happening right now... Indeed it let me see why Hong Kong is different from China. I received flyers and AirDrop - very smart act."
Hundreds of police lined the route, temporarily closing some roads and diverting public transport.
The organizer said 230,000 people had attended the march, while police put the number at 56,000 at its peak.
By 7:30pm (1130 GMT) most had left, but as the evening wore on several hundred regrouped and marched up a busy street toward the densely populated Mong Kok neighborhood, blocking traffic along the way.
Lines of police with helmets and plastic shields stopped their advance, and worked to disperse the group by driving them back, mostly peacefully. Live TV footage appeared to show a handful of protesters being detained after being wrestled to the ground.
Hong Kong's Tourism Association said some travel agencies stayed away from Tsim Sha Tsui on Sunday.
The extradition bill, which has left Hong Kong Chief Executive Carrie Lam clinging to her job, would cover Hong Kong residents and foreign and Chinese nationals living or travelling through the city. Protesters want the bill withdrawn altogether.
Lawyers and rights groups say China's justice system is marked by torture, forced confessions and arbitrary detention, claims that Beijing denies.
Lam has offered closed-door talks to students from two universities but activists said they want the discussions to be open to the public and called for a halt to investigations of protesters. Police began arresting protesters this week. (Additional reporting by Vimvam Tong, Twinnie Siu, Aleksander Solum, Twinnie Siu, Jessie Pang and Noah Sin Writing by John Ruwitch Editing by Paul Tait and Elaine Hardcastle)