Chile's armed forces rejected the "abusive and humiliating" decision by the British Home Secretary, Mr Jack Straw, and described the legal process against Gen Pinochet as a case of "state kidnapping".
"We are deeply upset," the Defence Minister, Mr Jose Florencio Guzman, said. But he stressed that relations between army and civilian institutions were "sufficiently solid" to withstand the storm.
Chilean President Eduardo Frei returned from Brazil yesterday and faces a tense meeting of the army-controlled National Security Council today. The 24-hour period before the Security Council meeting gave Mr Frei time to assess the mood on the streets before committing himself to a line of action with the armed forces.
No major incidents have been reported, although 51 Pinochet supporters were arrested by riot police in Santiago near the residences of the British and Spanish ambassadors.
Meanwhile 100 Chilean generals offered themselves as "willing hostages", prepared to go to prison in place of Gen Pinochet, while 2,000 army officers signed a petition demanding economic sanctions against Britain and Spain.
In a rare break from his usual diplomatic tones, Argentina's Foreign Minister, Mr Guido di Tella, told journalists he was "fed up to the teeth with the Spanish" and expressed relief that independence had been secured in 1810.
"This is going to be a delicate process for Chile," he added. (He might have also said it is delicate for Argentina, because Spanish extradition proceedings are also pending against former Argentine dictators.)
Mr di Tella spoke in Rio de Janeiro where he was attending a meeting of MERCOSUR, South America's version of the European Community. This week's summit centred on the Pinochet crisis. A change of heart by the host, Brazil's President Fernando Henrique Cardoso, secured a six-state declaration of support for the principle of territoriality, but omitted any direct reference to Gen Pinochet.
Bolivian President Hugo Banzer, a former army general, quickly signed up to the MERCOSUR declaration, fearing he might be next in line for the Pinochet treatment. Gen Banzer seized power in a bloody coup in 1971 and collaborated closely with Gen Pinochet in "Operation Condor", a cross-border reign of terror in which the region's security forces swapped prisoners and co-ordinated the assassination of dissidents living abroad.
Meanwhile, the Argentine parliament met at midnight on Wednesday to approve a special fund for the investigation of stolen children, and also to strip Gen Pinochet of the honours awarded him during a visit to Buenos Aires two years ago.
In addition, Judge Adolfo Bagnasco jailed former admiral Jose Suppicich on charges of child theft, while 28 lieutenant-colonels found their promotion blocked due to legal proceedings by the Grandmothers of the Disappeared.
"I am fed up with this," said army chief Gen Martin Balza. "Everything the army does is challenged by human rights organisations."
The soldiers in question are accused of participation in the torture and execution of political prisoners during military rule.