A series of shocking attacks in China signals a calculated bid by militants from mainly Muslim Xinjiang to raise the profile of their confrontation with Beijing -- whatever the cost, analysts say.

Their violent campaign, which was long concentrated against security authorities within the resource-rich region, has since late last year spread to civilian targets both inside Xinjiang and far beyond.

A fiery vehicle crash in Beijing's Tiananmen Square -- symbolic heart of the Chinese state -- last October was followed by a horrific knife assault in March at a railway station in the southern city of Kunming.

In what many in China dubbed the country's "9/11", 29 died and 143 were wounded in the bloody attack.

Last week assailants using knives and explosive devices attached to their bodies attacked a train station in Urumqi, Xinjiang's capital, resulting in three deaths -- including two alleged attackers -- and 79 wounded.

And on Tuesday a lone attacker was shot and caught after a slashing attack that injured six people at a station in the southern city of Guangzhou, police said, further fraying nerves.

Raffaello Pantucci, an expert at the Royal United Services Institute in London, called the apparent change in tactics a "worrying development" by militants who saw themselves as "part of an oppressed people who are not being recognised and supported".

"Obviously, people don't think that their message is getting through and that they're being heard," he told AFP. "If they're not being heard, then you have to make a louder sound.

"There may be some negative repercussions but the negative repercussions in some way will only feed the narrative that you're trying to advance."

- No claim of responsibility -

Tensions in Xinjiang have simmered for decades, with the Muslim Uighurs in the far western region claiming discrimination in religious practices and jobs in the face of immigration by China's Han majority. About 200 people died in inter-ethnic rioting in 2009.

China has vowed repeated crackdowns on violence in Xinjiang, most recently during a visit last week by President Xi Jinping, his first since assuming office last year.

He promised "decisive actions" against terrorism and called the Kashgar area the "front line in anti-terrorist efforts".

It borders Central Asia, from where some -- including Beijing -- say radicals of the Turkestan Islamic Party (TIP) and East Turkestan Islamic Movement (ETIM), influenced by Al Qaeda, inspire and even orchestrate violence in China.

Rohan Gunaratna, professor of security studies at Nanyang Technological University in Singapore, welcomed Xi's comments as long overdue.

"China now faces a very significant threat from terrorism emanating from the ideology and also by the training infrastructure that the Turkestan Islamic Party has established in North Waziristan" in Pakistan's tribal areas, he said.

The TIP "is currently recruiting, currently radicalising a number of Uighurs to conduct terrorist attacks", he told AFP, describing the recent incidents as "milestones" that heralded more "in the coming months and coming years".

Many other experts, however, question the influence of the TIP, a shadowy group that has released videos praising attacks in China but has yet explicitly to claim responsibility for them.

Nor, for that matter, has anyone else, said Sean Roberts, an expert on Uighurs at George Washington University in the US.

"Even if there is an organisation behind the attacks, it would likely be a homegrown organisation as opposed to an international organisation because for an international group, there would be some claim to take credit," Roberts told AFP.

"A lot of terrorism doesn't require much organisation at all," he added, citing last year's Boston Marathon bombings.

The US attack was "much more sophisticated than anything in these train stations, but yet it seems quite clear that it was just the work of two people and there was no outside organisation behind it", Roberts said.

Scott Harold, a China expert with US think tank Rand Corporation, told AFP: "ETIM is not central in any way to the broad concerns of Al Qaeda or any of the Sunni Islamist movements worldwide.

"It's marginal even compared to a group like (Nigeria's) Boko Haram, which is usually described as a marginal part of Al Qaeda," he said.

- 'Self-fulfilling prophecy' -

The night after the Urumqi violence, Beijing police held anti-terror drills at a key railway station in the centre of the capital.

Chinese authorities have yet to attribute a motive for the Guangzhou incident.

But Mao Shoulong, a professor at Beijing's Renmin University, said escalating violence was sure to be met with stronger measures by the government.

"The general reaction is likely that vigilance will be tightened nationwide." he said. "More police will be added and more training will be done."

Ultimately, though, a harsher response to the escalation is unlikely to prove a deterrent, according to Pantucci.

"All of that is only going to exacerbate the tensions and the sense of alienation in the community," he said.

"So it's kind of a self-fulfilling prophecy in some ways. From both sides it sort of feeds off each other."