Hong Kong was once considered a bastion of freedoms on China's doorstep, enjoying a separate and independent judicial system from China under a 'one country, two systems' arrangement since 1997.

Hong Kong police issued arrest warrants for eight overseas-based activists, accusing them of national security offences, including foreign collusion, and offered rewards for information leading to their arrest.

The activists are based in several countries, including the US, Britain and Australia.

The notices accused the activists of asking foreign powers to impose sanctions on Hong Kong and China.

Asean should state explicitly that executing dissenters is the ultimate act of violence and that it expects Myanmar to desist from such behaviour immediately.

Sentenced to death in January in a closed-door trial, the four men had been accused of helping militias to fight the army that seized power in a coup last year and unleashed a bloody crackdown on its opponents.