(Reuters) - Chinese police in the far western region of Xinjiang have taken down 23 "terror and religious extremism groups" and caught more than 200 suspects in May, state media said, days after the region's deadliest attack in years.

China has announced year-long "anti-terrorism" operations in restive Xinjiang, home to a large Muslim Uighur minority, as well as nationwide, following a series of bloody incidents that Beijing blames on Islamists and separatists from the region.

Police busted the groups in the southern Xinjiang prefectures of Hotan, Kashgar and Aksu and seized more than 200 explosive devices in raids, the official Xinhua news agency said late on Sunday.

Many of those captured were in their 20s and 30s, and had learned how to make explosives by watching online videos, Xinhua said.

"They exchanged their experiences of making explosives and propagating jihad through chatting tools, text messages and illegal preaching sites," the news agency said, citing the regional public security department.

China has said five suicide bombers carried out an attack at a morning vegetable market in Xinjiang's capital of Urumqi on Thursday, which killed 31 people and injured 94.

It was the second attack in Urumqi in just over three weeks, after a bomb went off at a train station in late April, killing a bystander and wounding 79.

"...must truly turn violent terrorists into rats scurrying across the street, with everyone shouting to beat them down," state media cited Zhang Chunxian, the ruling Communist Party chief in Xinjiang, as saying at a Sunday meeting on the latest Urumqi attack.

At least 180 people have been killed in attacks across China over the past year.

Beijing warns that separatist groups in Xinjiang are seeking to form their own state called East Turkestan.

But exiles and rights groups say the real cause of the unrest in the resource-rich region bordering central Asia is China's repressive policies that put curbs on Islam and the culture of Uighurs, Muslims who speak a Turkic language.

Uighurs have long complained of official discrimination in favor of the Han, China's majority ethnic group.