Ministers had intended to outlaw advertising of cigarettes on billboards and in cinemas, newspapers and magazines from December 10.

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However, an injunction granted to tobacco companies means that the government may have to delay its ban until the European Court rules whether an EU directive banning advertising is legal.

The legal challenge to the directive was brough by tobacco companies including Imperial, Gallagher, Rothmans UK and British American Tobacco supported by the Tobacco Manufacturers' Association.

They argued the government was jumping the gun in introducing a ban before their challenge had reached court and they sought a court order to stop ministers going any further.

Last month sitting in the High Court in London Mr Justice Turner said it was "arguable" the companies would succeed in their European Court challenge.

Until then, he said, the Government should be barred from making any regulations under the directive.

The government had argued that it was both in the national interest and in accordance with its manifesto pledges to implement the directive at a time of its choosing.

But Mr Justice Turner said this was no answer in law, and although he recognised the health benefits of the ban, the effect of a delay was unlikely to be significant.

Important constitutional issues

Speaking in the Court of Appeal on Monday, the government's counsel, Christopher Vajda QC, said the case raised important constitutional issues on the relationship between the role of the courts and Parliament's desire to express the will of the people.

He said the law lords would have to weigh the competing interests of the tobacco industry, which were essentially commercial, against the public interest as perceived by the UK Government and by the European Community's Council, Commission and Parliament.

"The policy of prohibiting tobacco advertising was in the Government's election manifesto," he said.

"The Government believes it is in the interests of public health."

The European case is expected to reach its conclusion some time towards the end of next year.

If the government appeal is not successful, the introduction of the ban could be delaed for at least a year.

Some backbench MPs say if that happens they will attempt to introduce a private member's Bill to ban tobacco advertising as soon as possible.

In a separate case which began on Monday in the High Court, the same tobacco companies sought judicial review of a Department of Health report on passive smoking.