Police have arrested 1,434 suspects in connection with the worst ethnic violence in decades in China's western Xinjiang region, which killed at least 156 people, state media reported Tuesday.

The arrests come amid a security clampdown on the region, with hundreds of paramilitary police with shields, rifles and clubs taking control of the streets of the capital, Urumqi, where the riots took place on Sunday.

The violence does not bode well for China's efforts to mollify long-simmering ethnic tensions between the minority Uighur people and the ethnic Han Chinese in Xinjiang — a sprawling region three times the size of Texas that shares borders with Pakistan, Afghanistan and other Central Asian countries.

Mobile phone service and the social networking site Twitter have been blocked, and Internet links also were cut or slowed down.

A nonviolent protest by 200 people was broken up in a second city, Kashgar, and the official Xinhua News Agency said police had evidence that demonstrators were trying to organize more unrest in Kashgar, Yili and Aksu.

It said police had raided several groups plotting unrest in Dawan township in Urumqi, as well as at a former race course that is home to a transient population.

The unrest in Urumqi began Sunday after 1,000 to 3,000 protesters gathered at the People's Square and protested the June 25 deaths of Uighur factory workers killed in a riot in southern China. Xinhua said two died; other sources put the figure higher.

Many Uighurs haven't been wooed by the rapid economic development. Some want independence, while others feel they're being marginalized in their homeland. The Han — China's ethnic majority — have been flooding into Xinjiang as the region becomes more developed.

The government often says the Uighurs should be grateful for the roads, railways, schools, hospitals and oil fields it has been building in Xinjiang, a region known for scorching deserts and snowy mountain ranges.

A similar situation exists in Tibet, where a violent protest last year left many Tibetan communities living under clamped-down security ever since.

"The Han Chinese say we all belong to the same country. We're all part of one big family," said Memet, a restaurant worker who like other Uighurs declined to give his full name because he feared the police. "But the Han always treat us separately."

A Han Chinese shopkeeper, who only gave his surname Wang because the ethnic issue is so sensitive, disagreed. "Those who cause such trouble are criminals," he said. "They're never happy with what they have."

Sunday's violence was notable because it happened in Urumqi, which has been relatively peaceful and hasn't been a hotbed of religious or political agitation. In other restive Xinjiang cities, red propaganda banners are filled with slogans encouraging ethnic harmony. But most of the banners in Urumqi touted anti-drug and fire prevention campaigns.

The population of 2.3 million is also overwhelmingly Han Chinese in the city, a mixture of drab concrete apartment blocks and gleaming new office towers.