'Protection of the national flag and the regional flag from desecration, having regard to their unique symbolism, will play an important part in the attainment of these goals,' he said.

'In these circumstances, there are strong grounds for concluding that the criminalisation of flag desecration is a justifiable restriction on the guaranteed right to the freedom of expression.' The Chief Justice, in a unanimous ruling, said the 'intrinsic importance' of the flags was demonstrated by the fact that they were raised at the handover ceremony.

The five judges overturned a ruling by the Court of Appeal in March that the laws, introduced after the handover, were unconstitutional.

Convictions against Ng Kung-siu and Lee Kin-yun, who waved 'extensively defaced' flags in a peaceful pro-democracy demonstration in January last year, were restored by the court. Their sentences, orders that they be bound over to keep the peace, were also reinstated. Both men are in their 20s.

After the ruling, solicitor Albert Ho Chun-yan, for Lee, said: 'I think this is another glaring example of a step back in our protection of freedom of expression after the return of Hong Kong to China.' Mr Ho, a Democratic Party legislator, said the ruling marked a disturbing trend, following the abolition of the municipal councils and the Government's right-of-abode victory earlier this month.

'We see there is a rollback in democracy. Now we also see that the freedom of expression for the Hong Kong people which was enjoyed before the handover has been taken away.' Hong Kong was becoming more like Singapore with regard to its laws and the protection of human rights, he added.

Secretary for Justice Elsie Leung Oi-sie brushed aside fears for freedom of expression. Other legal experts defended the ruling, which they said was supported by careful legal reasoning.

The Chief Justice had ruled the restriction imposed by the flag laws to be limited in that they only ban one form of expression. Protection of the flags was a legitimate interest of the community and the laws were necessary and justified, he said.

During the hearing in October, Audrey Eu SC, for Lee, had described the flag laws as being the beginning of the end for freedom of speech and had asked where the limits would be.

Mr Justice Kemal Bokhary, in his ruling, said: 'It is a perfectly legitimate question. And the answer, as I see it, is that it stops where these restrictions are located. For they lie just within the outer limits of constitutionality.

'Beneath the national and regional flags and emblems, all persons in Hong Kong are - and can be confident that they will remain - equally free under our law to express their views on all matters . . . saying what they like, how they like.'