BEIJING (REUTERS) - China charged four people for a deadly attack at a train station in the south-western city of Kunming in March, state media said on Monday, a case that prompted a nationwide crackdown on what officials have called an upsurge in militant violence.

The government has said knife-wielding militants from the restive western region of Xinjiang launched the premeditated attack on the Kunming Railway Station in Yunnan province in which 29 people were killed and 140 injured.

China's leaders have vowed to strike hard at religious extremists and separatist groups, which it blames for a series of violent attacks in Xinjiang, the traditional home of the Muslim Uighurs.