China is issuing harsh warnings against foreign meddling in Hong Kong's politics ahead of an expected announcement recommending restrictions to the first direct elections for the leader of the Chinese-controlled financial hub.

An article in the ruling Communist Party's flagship newspaper People's Daily on Saturday says some in the former British colony were colluding with outside forces to turn it into a bridgehead for subverting and infiltrating the Chinese mainland.

China's legislature on Sunday is expected to announce that an elite pro-Beijing body must vet candidates for the territory's leader starting from 2017. That has set up a showdown with pro-democracy groups who want the public to be able to nominate people freely.

Since being handed back from Britain in 1997, Hong Kong has retained a high degree of autonomy.