Serious threat

Europe has traditionally been the biggest market for Afghan opiates and opium cultivation in Afghanistan increased by 59% this year.

"Some cities take the problem more seriously than others. Illicit drugs are a serious threat to our young people and the very future of our societies," Mr Costa said in a statement.

Mr Costa said he has strongly encouraged the mayors and Europe's community drug centres to be on the alert and take every possible measure to deal with the threat.

Europe's politicians, he said, should take responsibility for what is happening in their own backyards, rather than expecting their drug problem to be solved by others.

"The violence we saw yesterday is not acceptable," Sarkozy told reporters after a cabinet meeting.

"These excesses will be severely punished. Violence is not acceptable in any line of work."

Wearing their fire helmets and uniforms, the firemen threw fire extinguishers, stones, bottles and fired flares towards police officers wearing riot gear.

Around 6000 firemen took part in the protest, according to police estimates.

The national fire-brigade union condemned the firemen's behaviour and attributed it to a few troublemakers. In a statement it said that the "criminal" and "extreme" behaviour had tarnished the image of all of France's firemen.

The recommendations, which have not been made public, still have to be reviewed by the traditionally conservative Vatican department responsible for safeguarding theological orthodoxy, and then by the Pope himself, before any decision is made.

The rethink, commissioned by Pope Benedict following his election last year, could save millions of lives around the world. It is likely to be raised today when the Archbishop of Canterbury, Rowan Williams, has his first full discussion with the Pope at an audience in the Vatican.

Campaigners and organisations involved in the fight against Aids have long been pressing the Vatican to change its stance on condoms, which they believe obstructs attempts to save millions of lives. Last year the head of HIV/Aids at the World Health Organisation initiated talks with the Vatican to see if any movement could be made on the issue.

The Mexican cardinal Javier Lozano Barragán, who heads the papal department responsible for health issues, revealed on Tuesday that he had completed the first stage of the review. A 200-page report, reflecting opinion within the church, had been sent to the Pope and the Congregation for the Doctrine of the Faith, the Vatican's "theology ministry", he said.

He did not reveal its conclusions. But Cardinal Barragán is known to favour reform and Vatican sources said it was highly likely that he had come out in support of using condoms in marriages where one of the partners was HIV-positive.

The Italian newspaper La Repubblica, which broke the news of the policy review earlier this year, reported yesterday that the Vatican would "go from prohibition to the definition of exceptional cases in which it would be possible for the faithful to use prophylactics to avert fatal risks".

Cardinal Barragán noted a passage from a 1981 document issued by the late Pope John Paul II. This said that "every conjugal act must be open to life".

Until now, this has been interpreted as an injunction against contraception. But it could also be used to support an argument in favour of the preservation of life by the use of barrier methods.

The cardinal said some 40 million people were reckoned to be HIV positive and Aids was claiming around 8,000 lives a day. "The disease is not retreating. On the contrary, its aggressiveness seems to be increasing, even though in the more developed countries the strength of the increase is noticed less," he said.

The first-hand experience of Roman Catholic missionaries and pastors in the developing world has been the driving force behind the current rethink. But it is also noted in the Vatican that the Pope, when he was in charge of the Congregation for the Doctrine of the Faith, left open the possibility of a change in the church's stance.

The 1987 document Donum Vitae, which he signed together with the late Pope, declared that the Roman Catholic church could never agree to the use of contraceptives in homosexual relationships or by men and women who were not married. However, it omitted to mention married couples. In recent years, the case for condoms as a defence against Aids has been taken up publicly by several Roman Catholic leaders. The Belgian cardinal Godfried Daneels broke the taboo in 2004 when he said it was morally different from using a condom for birth control.

The following year, the Pope's own theologian, Cardinal Georges Cottier signalled doubts within the papal household and argued that the Roman Catholic "theology of life" could be used to justify a lifting of the ban. "The virus is transmitted during a sexual act; so at the same time as [bringing] life there is also a risk of transmitting death," he said. "And that is where the commandment 'thou shalt not kill' is valid."

Cardinal Carlo Maria Martini, a former archbishop of Milan who was considered a candidate for the papacy, said earlier this year that a married person with HIV was "obliged" to protect his or her partner from the disease.

The Congregation for the Doctrine of the Faith, which will now consider the issue, was headed by Pope Benedict for 24 years before his election. After he became Pope, he appointed as his successor an American, Cardinal William Levada. For the previous 10 years, Cardinal Levada had been Archbishop of San Francisco - a city where the spread of Aids was a key issue and where Roman Catholic charities played a leading role in supplying care to sufferers. But the cardinal has not himself offered a view in public on the debate.

The Italian daily Corriere della Sera said the Pope's decision could be announced as early as next February, on the 20th anniversary of the publication of Donum Vitae.