(adds information about patrols, recasts)
BEIJING, May 12 (Reuters) - China tightened security in its capital on Monday, strengthening police patrols and restricting bulk purchases of gasoline, state media reported, in the wake of a string of violent attacks by militants.
Beijing police sent out 150 armed patrol vehicles into the city on Monday, the official Xinhua news agency reported, "countering street terrorism and fighting severe violence".
China has grown increasingly nervous about domestic unrest and Islamist militants since a car burst into flames on the edge of Beijing's Tiananmen Square in October. In March, 29 people were stabbed to death at a train station in the southwestern city of Kunming.
The patrol vehicles, which will be stationed at crowded intersections on main thoroughfares, will specifically guard against incidents involving guns, bombs and mass violence, Xinhua added.
Beijing will also require buyers of gasoline in bulk to register their names and intended use of the fuel, the official People's Daily reported on Monday.
Those seeking to buy gasoline must first register at their local police station to "prevent law-breakers from using gasoline to create disturbances", the paper reported.
Exile groups and rights activists say China's heavy-handed policies in the restive western region of Xinjiang, home to the Muslim Uighur people, have sowed the seeds of unrest.
Xinjiang, resource-rich and strategically located on the borders of central Asia, has been plagued by violence for years, blamed by the government on Islamist militants and separatists.
Police last week shot dead an assailant who attacked a police vehicle with knives in Xinjiang.
(Reporting by Megha Rajagopalan; Editing by Nick Macfie)