URUMQI - Police have thwarted several attempts to sabotage public safety in the run-up to an international trade fair to be held in the country's northwest, a senior local official said.

Zhu Hailun, the Party chief of Urumqi in the Xinjiang Uygur autonomous region, told reporters on Wednesday, one day before the opening of the China-Eurasia Expo, that separatists, religious extremists and terrorists have been plotting to sabotage the expo.

He confirmed that airport security staff in Urumqi on Aug 7 arrested a man who attempted to take a knife on board. He has been detained on suspicion of planning to carry out an attack during the flight.

"There have been many similar cases of attacks being blocked by police," Zhu said. "Hopefully we have intervened in time to nip the violence in the bud."

Authorities have boosted security in Urumqi in the run-up to the first China-Eurasia Expo. Airports in a dozen cities, including Beijing and Shanghai, have tightened security screenings for Urumqi-bound flights since Sunday. Passengers have been asked to remove their shoes and let their carry-on luggage be opened and searched.

Fully-armed police are guarding the convention venue in suburban Urumqi while armored vehicles are parked in front of high-end hotels where the dignitaries are staying.

The increased security comes amid a two-month crackdown on terrorism ordered by regional authorities earlier this month following an outbreak of violence in Xinjiang's major southern cities, Kashgar and Hotan, that left at least 40 dead and dozens injured.