After hearing seven hours of arguments, the judge said he would rule on Monday on an application from the government for an injunction barring the unlicensed station from broadcasting.

He said the station could go back on the air in the meantime, after accepting a promise from its director, Tsang Kin-shing, that Citizens' Radio would broadcast for only an hour a day on FM 102.8.

But the judge warned this should not be taken as an indication of what his decision would be on Monday.

Mr Tsang said he would discuss with fellow activists whether to broadcast over the weekend.

The reprieve was the latest twist in a court saga that began when a magistrate last week ruled the broadcast licensing law to be unconstitutional - dismissing charges against Mr Tsang and five fellow activists - but then suspended the ruling pending an appeal by the government.

The government obtained the temporary High Court injunction on Thursday last week from Mr Justice Barnabas Fung Wah, who said the order was imposed to safeguard the public safety and interest.

But Citizens' Radio kept broadcasting and the Justice Department has since launched contempt of court proceedings.

Yesterday, Mr Justice Hartmann acknowledged that the broadcasters believed their acts were not unlawful after the January 8 ruling by Magistrate Douglas Yau Tak-hon that the licensing provisions in the Telecommunications Ordinance were unconstitutional. In his ruling, Mr Yau said the ordinance gave the chief executive 'unfettered and unchecked' power to control who could conduct radio broadcasts and breached freedom of expression provisions in the Bill of Rights and the Basic Law.

Mr Justice Hartmann said: 'I do not see there is any danger or hazard to society. I do not see [Citizens' Radio] is acting in open defiance of the law, knowing that they are breaching the law.'

But he warned the broadcasters that as the appeal against the magistrate's ruling was under way, they still ran the risk of prosecution if police arrested them under the Telecommunications Ordinance.

Senior counsel Jat Sew Tong, for the government, argued yesterday that the continuous unlicensed broadcasting of Citizens' Radio was a breach of the law after Mr Yau had suspended his ruling.

He said the broadcasts created a potential danger to society from radio interference as it could encourage the setting-up of more unlicensed broadcasters.

He said there was evidence from the Broadcasting Authority suggesting that interference had occurred on frequencies in the radio spectrum.

The authority received about 3,000 complaints a year, although none about Citizens' Radio, which began operations in 2005.

For Citizen's Radio, senior counsels Philip Dykes and Martin Lee Chu-ming said the suspension did not provide temporary validity to the law, which had been ruled unconstitutional. Rather, it allowed the government to operate without the embarrassment of conflicting with the ruling of unconstitutionality.