Police in China's restive Xinjiang region have launched a fresh manhunt aimed at capturing fugitives wanted in connection with deadly ethnic violence in July this year, state media said Tuesday.

The regional public security bureau's "strike hard and rectify" campaign, which began on Sunday, will run until the end of the year, the Xinjiang Daily reported.

"We must expand the scope of our work on capturing fugitives, do better to gather, analyse and research all intelligence and focus on cases and clues related to violent acts of terrorism," said the report, citing Xinjiang police.

"We must strictly prevent violent acts of terrorism and ensure stability."

Violence between mainly Muslim Uighurs and members of China's dominant Han ethnic group erupted on July 5 in the regional capital Urumqi, leaving nearly 200 people dead, according to the official toll.

Last month, 21 people were convicted for their roles in the unrest, with 12 sentenced to death. Those sentences were upheld in appeal hearings last week.

According to the US-based Uighur American Association, a court in Yili prefecture, some 500 kilometres (300 miles) west of Urumqi, last week jailed 19 people for state security crimes, some linked to the July unrest.

Authorities have blamed the Xinjiang unrest on "ethnic separatists", without providing any evidence.

But Uighurs say the violence was triggered when police cracked down on peaceful protests over a brawl in late June at a factory in southern China that state media said left two Uighurs dead.

Human Rights Watch said last month that they had documented at least 43 Uighurs, including children, who remain unaccounted for after earlier round-ups by security forces following the clashes.

The real number could be much higher, the New York-based group said. China"s roughly eight million Turkic-speaking Uighurs have long complained of religious, political and cultural oppression by Chinese authorities, and tensions have simmered in Xinjiang for years.

China says it faces a serious terrorist threat from Muslim separatists in the region, but rights groups have accused Beijing of exaggerating the threat in order to justify its tight controls.

The new security crackdown comes one month after the 60th anniversary of the founding of communist China on October 1, during which security forces maintained calm in Xinjiang, the newspaper said.