(Adds U.S. description of attack as act of terror, in paragraphs 14-15)
By Michael Martina
URUMQI, China, May 1 (Reuters) - An attack at a train station in China's western city of Urumqi was carried out by two religious extremists who both died in the blast, the government said on Thursday.
Three people were killed, including the assailants, and 79 wounded in a bomb and knife attack at the station on Wednesday, according to the government and state media, as President Xi Jinping was wrapping up a visit to the area.
The Xinjiang regional government said on its official news website (www.ts.cn) that the two attackers who were killed had "long been influenced by extremist religious thought and participated in extremist religious activities".
It identified one of them as Sedierding Shawuti, a 39-year-old man from Xayar county in Xinjiang's Aksu region. The man is a member of the Muslim Uighur minority, judging by his name.
It did not identify the other person. The third person who was killed was a bystander, the government said.
The People's Daily, the official newspaper of the ruling Chinese Communist Party, said earlier on its microblog that "two mobsters set off bombs on their bodies and died".
But the newspaper did not call it a suicide bombing.
Xinjiang, resource-rich and strategically located on the borders of central Asia, has been beset by violence for years, blamed by the government on Islamist militants and separatists.
Exiles and many rights groups say the real cause of the unrest is China's heavy-handed policies, including curbs on Islam and the culture and language of the Uighur people.
The Wednesday blast was the first bomb attack in the capital of Xinjiang in 17 years. It came soon after the arrival of a train from a mainly Han Chinese province, state media said.
The Xinhua news agency earlier cited police as saying "knife-wielding mobs" slashed at people at an exit of the station and set off explosives.
The bombing was possibly timed to coincide with a visit to the region with a large Muslim minority by President Xi, when security was likely to have been heavy. State media did not say whether Xi, who was wrapping up his visit to the region, was anywhere near Urumqi at the time.
The government called the attackers "terrorists", a term it uses to describe Islamist militants and separatists in Xinjiang who have waged a sometimes violent campaign for an independent East Turkestan state.
In Washington, the State Department said all signs pointed to the attack being the work of terrorists.
"Based on the information we have seen, including what has been reported by the Chinese media, this appears to be an act of terrorism that targets random members of the public," State Department spokeswoman Marie Harf told a daily briefing.
On Thursday, dozens of police vans were parked around the station, while camouflaged police with assault rifles patrolled its entrance. Despite the security, the station was busy and appeared to be operating normally.
Pan Zhiping, a retired expert on Central Asia at Xinjiang's Academy of Social Science, described the attack as well organised, saying it was timed to coincide with Xi's visit.
"It is very clear that they are challenging the Chinese government," he said.
"There was a time last year when they were targeting the public security bureau, the police stations and the troops. Now it's indiscriminate - terrorist activities are conducted in places where people gather the most."
There has been no claim of responsibility.
In remarks released on Thursday from Xi's trip to Xinjiang, the president urged troops there to "strike crushing blows against violent terrorist forces and resolutely strike against terrorists who are swollen with arrogance".
"Resolutely crush the space for terrorist activities and contain the spreading trend of escalation," Xi said.
"ACT OF DEFIANCE"
Nicholas Bequelin, a senior researcher at New York-based Human Rights Watch who follows developments in Xinjiang, called the attack "an unprecedented act of defiance from Uighurs who oppose the Chinese state".
"It's hugely significant and it's extremely politically embarrassing for Xi Jinping who has taken a very hard stance on the Xinjiang issue, and made a big show while visiting Xinjiang that Xinjiang is safe for the Han," he said.
It was also the largest militant attack in Urumqi since the government blamed Uighurs for stabbing hundreds of Han Chinese with needles in 2009.
No one was killed in that incident, but it led to protests demanding the removal of the region's top official for failing to protect Han people, China's majority ethnic group.
Earlier that year, almost 200 people died in ethnic riots in Urumqi. Bombs on buses there killed nine people in 1997.
The city is heavily populated by Han Chinese, who have flooded there seeking business opportunities. Uighurs have complained that they have been frozen out of the job market.
"I just don't believe it was a Uighur who did this," said one 35-year-old Uighur man selling dried fruit about 100 metres from the blast site. "These public spaces aren't safe for anyone, Uighur or Han."
EXILES BLAME HEAVY-HANDED RULE
The attack came on the eve of a two-day Labour Day holiday, a time of heavy travel in China.
"Everyone was running and hiding. I was terrified," said Li Tianlin, a 53-year-old labourer. "We are still afraid and don't dare go over to the train station."
Xinhua condemned the spokesman for the German-based World Uyghur Congress exile group for saying that "such incidents could happen again at any time".
The spokesman, Dilxat Raxit, said in a email that more than 100 Uighurs had been detained since the attack, adding that Xi's visit was being used by the government as an excuse to step up "armed repression" in Xinjiang.
"Any provocation by China will directly inflame the situation and further worsen the unrest," he said.
Luo Fuyong, a spokesman for the Xinjiang government, rejected Raxit's accusations. "This is deliberate hostile rumour-mongering," Luo told Reuters by telephone.
Wednesday's attack was the latest in a spate of violence blamed by the government on Uighur militants.
In March, 29 people were stabbed to death in the southwestern city of Kunming. Five months earlier, a car ploughed into tourists on the edge of Beijing's Tiananmen Square, killing the car's three occupants and two bystanders.
Unrest in Xinjiang has caused the death of more than 100 people in the past year. (Additional reporting by Sui-Lee Wee, Li Hui and Ben Blanchard, Writing by Sui-Lee Wee; Editing by Ron Popeski, Robert Birsel and Ken Wills)