Chinese citizens must register their identities when they buy potentially deadly knives, Xinhua quoted the Ministry of Public Security on Tuesday as saying.

The new regulations come as China steps up security ahead of the Beijing Olympics.

The targeted daggers include those with blood grooves, lock-knives, and knives with blades measuring over 22 centimeters, the ministry said in a circular posted on its website, www.mps.gov.cn.

Police departments at all levels should check knife manufacturers for illegal production of deadly weapons, it said.

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Regulations concerning knife tools used by China's ethnic groups are to be set by local autonomous governments, the report said.

All parcels addressed to Olympic athletes, dormitories and sporting venues will be subject to X-ray checks, media reported on Tuesday.

China, whose Communist rulers value stability above all else, has come down hard on anyone they fear could upset the Games, from people protesting against the demolition of their houses for venues to the country's sometimes restless ethnic minorities.