Prosecutors have called on police to give more training and support to staff working at long-distance bus stations, to tackle drug trafficking via public transport.

In the past five years, coaches between cities have replaced airlines and railways as the main means to transport drugs, according to Beijing No 2 People's Procuratorate.

Many traffickers prefer long-distance coaches in China over airplanes and railways where they must provide proof of identity, said Zhang Ting, a senior prosecutor in the authority.