Officials in China’s remote western Xinjiang region say security forces have stopped several plots to sabotage the China-Eurasia Expo, which opened Thursday in the regional capital of Urumqi.

Among the dignitaries in attendance are Pakistani President Asif Ali Zardari and Kyrgyz President Roza Otunbayeva.

Zhu Hailun, the head of Urumqi’s Communist Party, told China’s state-run Xinhua news agency that a man was arrested at the city’s airport in August as he tried to board a flight carrying a knife. Zhu said the man has been detained on suspicion of planning to carry out an attack during the flight.

Zhu said police have blocked similar plots by “separatists, religious extremists and terrorists” plotting to sabotage the expo, but did not provide any specifics.

Security was increased in Urumqi ahead of the expo, which aims to cement the city’s place as the main trading hub between China and Central Asia.

Security forces launched a two-month crackdown in Xinjiang in mid-August following a wave of violence that left 30 people dead. Beijing says Islamic religious extremists are behind the unrest, but exile groups representing the region’s native Uighur population say repressive Chinese rule is the real cause.

The Uighurs are a mainly Muslim, Turkic-speaking people, who claim they are economically and culturally disadvantaged compared to growing numbers of Han Chinese moving into the region.

Tensions have been high in the region since 2009, when at least 197 people were killed during ethnic rioting between Uighurs and Han Chinese.