Sixteen people were killed in a clash in China's restive Xinjiang region, home to the mostly Muslim Uighur minority, reports and activists said Monday, less than two months after a fiery attack in Tiananmen Square.

Police attempting to detain criminal suspects in Shufu county near the Silk Road city of Kashgar, deep in far western China, were attacked by several "thugs" armed with explosive devices and knives, reported the tianshannet news portal, which is run by the Xinjiang government.

Two police officers were killed and 14 of the "thugs" shot dead on Sunday, it said.

But an overseas Uighur rights group said police had broken into a house where members of the ethnic minority were "gathering" and opened fire first.

All 14 people killed by police were Uighurs and two of them were minors, Dilxat Raxit, a spokesman for the Munich-based World Uyghur Congress, told AFP.

"The abusive use of force by authorities in the area has deprived the Uighurs of their right to live," he said.

Early Tuesday, China's official Xinhua news agency reported that six suspects have been captured.

An initial probe has revealed the 14 "terrorists" shot dead were from a group promoting extremist religious ideas and making explosives for terrorist attacks, Xinhua said citing a Xinjiang police official.

The incident comes less than two months after an attack in Tiananmen Square, the symbolic heart of the Chinese state, when according to police, three Xinjiang Uighurs ploughed into crowds of tourists, killing two people and injuring 40, before crashing outside the Forbidden City and setting their vehicle ablaze.

All three attackers -- named by authorities as Usmen Hasan, his wife and his mother -- died.

Beijing described the assault, the first blamed on Uighurs outside Xinjiang, as "terrorism" and said separatists backed by the militant East Turkestan Islamic Movement were responsible.

But outside experts pointed to the unsophisticated nature of the attack and the lack of an established Islamist extremist foothold in China.

Xinjiang, a vast area bordering Pakistan and Central Asia beyond the furthest reaches of the Great Wall, has followed Islam for centuries.

For years it has seen sporadic unrest by Uighurs which rights groups say is driven by cultural oppression, intrusive security measures and immigration by China's Han majority, but Beijing attributes to religious extremists, terrorism and separatism.

China's foreign ministry spokeswoman Hua Chunying said the latest incident "shows once again the anti-human and anti-society nature of the terrorist groups".

"This kind of attempt will not win public support and is doomed to failure," she told reporters at a briefing.

Authorities in Kashgar were not immediately available for comment when contacted by AFP.

In the worst outbreak of sectarian violence in recent years, around 200 people died and more than 1,600 were injured and hundreds arrested in riots in the regional capital Urumqi in 2009.

A total of 11 people -- nine attackers and two auxiliary police officers -- were killed in an attack on a police station in Serikbuya township near Kashgar last month, according to Xinhua.

Another incident in June in the Turpan area left 35 people dead, and 139 people have been arrested in recent months for spreading jihadist ideology.

Information in the area is tightly controlled and difficult to independently verify.

In August, a Chinese policeman was killed in an incident in Yilkiqi described by state media as an "anti-terrorism" operation, but overseas media said 22 Uighurs were shot dead in the confrontation.

More than 190 "terrorist" attacks were logged in Xinjiang last year, rising "by a significant margin" from 2011, state media reported last month.

Most of the attackers were in their early 30s or younger and increasingly act in small groups or individually as "a lone wolf", they added.

At a meeting last week, top Turpan officials said violent "terrorists" remained active in the area despite the authorities' "strike hard with high pressure" campaign, according to a statement posted on a government site.

They ordered local officials to chart a "relationship tree" of links between students in Turpan and those overseas, it said.

China arrested more than 1,000 people for "endangering state security" -- a charge commonly brought against ethnic minorities -- in 2012, up nearly 20 percent from the previous year, the US-based Dui Hua Foundation said last month citing official figures.

More than 75 percent of trials for suspects accused of the crime took place in Xinjiang, it added.

The offence replaced that of "counter-revolution" in the 1990s, and is primarily aimed at suppressing political dissent.

It applies to "splittism", or attempts to advocate independence for regions of China, as well as actions including espionage.