We must wage a war against organized crime, against banditry in Brazil, and against impunity

President Cardoso

Mr Daniel was a key political figure in the country's Workers' Party.

He was one of several mayors from the party to receive death threats late last year from a group apparently unhappy with its centrist tendencies, strengthening suspicions that his murder was politically motivated.

The Brazilian Revolutionary Action Front, which reportedly signed the letters, claimed responsibility for the killing in September of another mayor, Antonio da Costa Santos, in nearby Campinas.

Killers sought

The BBC's Jan Rocha in Sao Paolo says police have launched a massive manhunt for Mr Daniels' killers, setting up road blocks all over the city.

Daniels attempted to stamp out corruption

Mr Daniel's death is the latest in a series of violent crimes to sweep Brazil.

On Saturday, a leader of Brazil's land reform movement, Jose Rainha Junior, was shot and injured as he escaped an ambush in the west of Sao Paulo state.

Kidnapping in Sao Paulo state more than quadrupled last year with 267 cases reported up to November.

Faced with a surge in violence, the Brazilian Government is drawing up new measures to try to combat gang warfare and organised crime.

These include a bigger role for the federal police in crimes currently handled by the state police forces.

Man of the people

Thousands of people followed the funeral cortege through the streets of Santo Andre to the cemetery, while thousands more lined the route, waving white banners, flags and handkerchiefs. to say farewell to Celso Daniel, who was twice re-elected as mayor.

President Cardoso: Disgusted

Our correspondent says the killing of a man known for his efforts to improve social conditions and stamp out corruption has caused bewilderment, sorrow, shock and anger among Brazilians.

President Fernando Henrique Cardoso said he was disgusted by Mr Daniel's killing.

"We must wage a war against organized crime, against banditry in Brazil, and against impunity," he said.

Political strategist

Mr Daniel was last seen on Friday night, when he was abducted by a gang of eight armed men as he was driving home from a restaurant.

The gang forced his car off the road and captured him after a brief gun fight.

He was considered to belong to the moderate wing of the Workers' Party and was a good friend of Luiz Inacio Lula da Silva, the party president and current favourite to win October's presidential elections.

Mr Daniel was the party's political co-ordinator.