URUMQI - Two Tajik women who tried to smuggle 945 grams of heroin into China by hiding it in the soles of their shoes were caught at a northwest China airport, local customs officials said Thursday.

The pair, who claimed to be mother and daughter, were caught after arriving at the Urumqi airport in northwest China's Xinjiang Uygur autonomous region from Dushanbe on Dec 8, officials said.

The younger woman raised suspicions when she refused to put her shoes through the X-ray scanner. Customs officials poked the bottoms of the shoes with a needle and found two packets of heroin.

The pair have been placed in custody pending a police investigation, local officials said.

Nearly 5 kg of smuggled drugs have been confiscated at the Urumqi airport so far this year, customs officials said.

China has strict laws against drug-related crimes. According to the national penal code, smuggling 50 grams or more of drugs is a crime punishable by death.