By Ben Blanchard and Joseph Campbell

BEIJING (Reuters) - China vowed on Thursday to bring to justice those responsible for killing one of its citizens after Islamic State said it had executed a Chinese captive, the only known Chinese hostage to have been held by the group.

Islamic State said it had killed a Chinese and Norwegian captive, showing pictures of what appeared to be the dead men under a banner reading "Executed" in the latest edition of its English-language online magazine, Dabiq.

It did not give any details in the magazine, published on Wednesday, about how, when or where the men were killed.

In a brief statement, China's Foreign Ministry confirmed the man's identify for the first time, naming him as Fan Jinghui, saying he had been "cruelly murdered". It said in September one of its citizens appeared to be in Islamic State captivity.

Beijing had activated an emergency mechanism to try to rescue him, but he was killed nevertheless in a "cold-blooded way", the ministry said. It gave no details on how they might have captured him.

"The Chinese government strongly condemns this savage act devoid of humanity and will certainly bring the criminals to justice," the statement said.

"The Chinese government will resolutely oppose all forms of terrorism and resolutely strike at any violent terrorist criminal activities that defy the bottom lines of human culture," it added, noting Beijing would strengthen anti-terrorism cooperation with the international community.

Speaking at a later briefing, ministry spokesman Hong Lei did not elaborate on the statement.

Chinese President Xi Jinping, visiting Manila for a regional summit, said he strongly condemned the killing.

The militant group had previously identified Fan as a 50-year-old freelance consultant from Beijing.

The state-run Beijing News said Fan was a former advertising executive who had once lived in a western suburb of Beijing, but that his company shut down in 2003. It said it had found an advertising firm registered to Fan in western Beijing.

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Security officials stood guard outside the low-rise building on Thursday and stopped a Reuters reporter from entering.

"He was just a normal person. I didn't really know him when he lived here but there was nothing special about him," said one resident, who gave her family name as Zhang.

SEEKING DANGER

While Chinese workers in Africa and Pakistan have been held hostage before, a diplomatic source familiar with the case said it was unclear what exactly Fan was doing in the Middle East, but it appeared he had a "wanderlust".

"It seems he wanted to see unusual places and this is probably why he ended up there," the source, speaking on condition of anonymity, told Reuters.

Influential state-run tabloid the Global Times cited an interview Fan gave to Chinese state television in 2001 in which he said he had a sense of adventure - and danger.

"I sedulously seek out a feeling of 'un-safety', because it gives me a kind of pleasant sensation once the danger is past," Fan said.

China has repeatedly denounced Islamist militants and urged the world to step up coordination in combating Islamic State, though it has been reluctant to get involved on the ground in Syria and Iraq where the group largely operates.

Chinese officials say the country faces a severe threat from Islamist separatists in its western Xinjiang region, where violence has left hundreds dead over the past three years.

The government says some Muslim Uighurs have gone to fight with radical groups in the Middle East.

Western nations have been reluctant to cooperate in China's campaign in Xinjiang, nervous about being implicated in possible human rights abuses. China denies rights abuses in Xinjiang.

Since last week's attacks in Paris, Chinese state media has lambasted Western countries for their "double standards" on terrorism. The Global Times said on Thursday the West probably deserved no sympathy from China.

"The West only recognizes its own style of democracy and accepts only the terrorism it suffers," it said in an editorial.

(Editing by Michael Perry and Nick Macfie)