BEIJING (Reuters) - China charged four people in connection with a deadly attack at a railway station in the southwestern city of Kunming in March, state media said on Monday, a case that helped spur a crackdown on what officials have called an upsurge in militant violence.

Police investigate after a group of armed men attacked people at Kunming railway station, Yunnan province, March 1, 2014. At least 27 people have been killed in the "violent attack" at the train station in Kunming, the Chinese state news agency Xinhua said on Sunday. Another 109 were injured, the report added. REUTERS/Stringer

The government has said eight knife-wielding militants from the restive western region of Xinjiang launched a premeditated attack at Kunming station in Yunnan province in which 29 people were killed and 140 injured. Police shot four of the attackers dead.

China’s leaders have vowed to strike hard at religious extremists and separatist groups, which they blame for a series of violent attacks in Xinjiang, the traditional home of the Muslim Uighur ethnic minority.

“The Kunming Municipal People’s Procuratorate found that the suspects were involved in organising, leading or taking part in the terrorist attack as well as intentional homicide,” the official Xinhua news agency said, citing the prosecutor.

“The crimes of the four defendants are clear and the evidence is abundant,” the prosecutor said.

The Kunming attack was one of the single deadliest incidents attributed by the government to militants. A suicide bombing in May killed 39 people at a market in Xinjiang’s capital, Urumqi.

Authorities had laid out the charges in March, but have now formally filed them, paving the way for an imminent trial. The four surviving defendants, all of whom have Uighur names, are likely to be given the death penalty.

Courts in China are controlled by the ruling Communist Party, making it unusual for those accused of crimes - particularly in politicised cases - to have a fair trial.

Xinjiang, resource-rich and strategically located on the borders of central Asia, is crucial to China’s growing energy needs. Analysts say that much of the proceeds have gone to the majority Han Chinese, stoking resentment among Uighurs.

Exiled Uighur groups and human rights activists say the government’s repressive policies in Xinjiang, including controls on Islam, have provoked unrest, a claim Beijing denies.

Courts in Xinjiang had sentenced 113 people to jail terms ranging from 10 years to life for terrorist activities and other crimes, the Xinjiang government said.

The sentences were handed down on Wednesday by courts in 11 counties and cities in the Kashgar region, Xinjiang’s official Tianshan news website said late on Sunday.

It did not identify the ethnicity of those sentenced, but they had Uighur names.

Those sentenced were accused of crimes such as “being involved in organising, leading and participating in a terrorist organisation, inciting ethnic hatred and ethnic discrimination”, bigamy, drug trafficking, robbery among other crimes, the Tianshan news report said.

There is now a “competitive race” among various areas to arrest and sentence Uighurs, Dilxat Raxit, spokesman for the World Uyghur Congress, the largest group of exiled Uighurs, said in an email.

“Uighurs who have revolted and expressed dissatisfaction against China’s repression are now accused of terrorism,” Raxit said.

At least 380 people have been detained in the last month in a sweeping crackdown on violence in Xinjiang.

State media last month reported a public mass sentencing, reminiscent of China’s revolutionary era rallies, attracting a crowd of 7,000 at a sports stadium in Yining city in the northern prefecture of Yili.

Around 200 people have died in unrest in Xinjiang in the past year or so, the government says, including 13 people shot dead by police in an attack on a police station in mid-June.