Earlier this week, a judge had ruled that the city's licensing laws infringed on its celebrated freedom of speech, but the ruling remained suspended pending a government appeal.

The ruling had thrown open the legality of the city's Telecommunications Ordinance.

If it stands, it would overturn the illegal broadcasting charge that was slapped on five pro-democracy activists behind Citizens' Radio, including radical lawmaker 'Long Hair' Leung Kwok Hung.

However, Mr Leung, along with last night's guest speakers at a broadcast made off the streets at the Mongkok shopping belt, could yet be charged with the same offence a second time, given that the ruling had not taken effect.

In addition, officials also obtained a further injunction yesterday to ensure that heavier punishment could be imposed if the broadcast went ahead.

On Tuesday, a local magistrate ruled that Hong Kong's licensing regime was unconstitutional, as not only was the application process unclear, too much discretionary power also lay in the hands of the Chief Executive.

This, he ruled, violated the right to free speech and expression under Hong Kong's constitutional Basic Law.

However, the court ruled again yesterday, following the temporary injunction, that there was a need to control the airwaves, in case essential channels reserved for law enforcement and emergency services were affected.

Speaking at a press briefing, the Secretary for Commerce and Economic Development said that 'illegal broadcasting and freedom of speech are separate issues'.

Hong Kong, he added, 'must upkeep its strong rule of law'.

But pro-democrats slammed officials for 'targeting' efforts to rally support for a protest march on Sunday to call for universal suffrage in 2012.

In a landmark ruling, Beijing's central government said last month that it would consider implementing the one-man, one-vote system in Hong Kong in 2017 - but not any earlier.

The issue - Hong Kong's most controversial one for over two decades - has sparked most of the city's frequent demonstrations.

Pro-democrats have long claimed that the city's radio licensing laws are aimed at curbing dissent, and should be reviewed to better reflect expressions of freedom.

Last year, veteran pro-democrat Szeto Wah famously said that he would rather go to jail than lose his freedom of speech, after being accused of taking part in an illegal Citizens' Radio broadcast.

Last year, officials had also rejected an application for a licence from the station, which has been operating on-and-off since October 2005.

While expressing disappointment at the injunction, Mr Leung and other activists continued to air after 7pm yesterday a public discussion forum that drew a large crowd of passers-by.

Guest speakers included fellow pro-democracy lawmakers Emily Lau, Lee Wing Tat and Lee Cheuk Yan.

'For democracy, we have decided to risk contempt of court,' radio operator Tsang Kin Shing told the crowd.

'Moreover, we have never before interfered with any crucial or emergency channels.'

vincec@sph.com.sg