It was an attempt to spread panic and anxiety, to suffocate every peaceful debate, to create a deep fissure in Italian society

Claudio Scajola Interior Minister

A man saying he represented the brigades earlier claimed responsibility, and a symbol of the group was found scratched into the wall of Biagi's house.

The assassination has sent shockwaves through Italy and deepened the existing divide between the government and the unions over reforms to labour laws.

They have rejected a plea by Prime Minister Silvio Berlusconi to abandon a proposed general strike following the murder.

Biagi, a senior aide who was involved in drafting the proposed laws, was gunned down by two men on a motorcycle outside his home in central Bologna.

His killing has raised fears of a resurgence of the political violence that plagued Italy during the 1970s and 1980s.

"In honour of Marco Biagi, a man of dialogue, we have decided to present a formal invitation to the social partners to resume negotiations immediately," said Mr Berlusconi, making clear however that his government intends to press ahead with reform.

But Italy's three biggest unions rebuffed the invitation, announcing that they would meet next week to set a date for a general strike in April.

They also called a nationwide strike for two hours on Wednesday to demonstrate against Biagi's death.

Tens of thousands gathered in the centre of Bologna to pay their respects in a rally organised by the unions.

'Deep fissure

Correspondents say the assassination has thoroughly rocked the country.

Marco Biagi wanted dramatic changes to the workers' statute

Mr Scajola cut short a visit to the United States to return to Italy, where he told an emergency session of parliament that the attack had been designed "to create a deep fissure in Italian society".

The country's main labour leaders were quick to denounce the attack, and Pope John Paul II has also joined the groundswell of outrage, branding the assassination "barbarous".

The Italian Football Federation has also decided to observe a minute's silence at all matches as a mark of respect for the murdered adviser.

Biagi is to be given a state funeral.

Terrorist legacy

A few weeks ago, the Justice Ministry warned that Italy could witness a revival of politically-motivated terrorism.

On 26 February, a bomb exploded near the Interior Ministry in Rome.

During the 1970s and 1980s, Italy was plagued by domestic attacks from both right-wing and left-wing extremists, which killed hundreds and left a legacy of lingering political hostility.

The group carried out many attacks in the 1970s - most notoriously the 1978 killing of former Prime Minister Aldo Moro.

Most of the leaders of the original Red Brigades were finally caught and sentenced to long prison terms.