The country's leading drugs lord has again demonstrated his ability to control things and dictate terms to the government, whether in jail or out, writes Timothy Ross in Bogota.

Colombia's leading drug trafficker, Pablo Escobar , was on the loose last night after a violent escape provoked by government efforts to move him to an army barracks jail from the ranch-style prison complex which he had turned into a bandit fortress. His escape came amid overwhelming evidence that 13 months after he surrendered to the authorities, he was continuing to plan and execute crimes from the security of his cell, with the complicity of prison guards.

The events discredit the Colombian government programme of negotiated surrender.

As hundreds of soldiers scoured the jungle-clogged slopes of the Andes for Escobar yesterday, the escaped Medellin cartel chief and his nephew phoned a radio station and said he was willing to surrender.

A man claiming to be Escobar told the Caracol radio network he first wanted guarantees of safety. Caracol said it was convinced the caller was Escobar , based on comparisons with voice recordings. Escobar 's nephew, Nicolas Escobar , later phoned to confirm the offer.

In a communique, Escobar said he wanted guarantees for his life and for a fair trail. He also wanted the United Nations to control entry to his prison.

Escobar , his brother, and eight other cartel members escaped from a jail near Medellin on Wednesday after the Colombian government bungled an attempt to transfer him to a military jail.

Caracol radio said Escobar and his nephew did not stay on the line long enough to say why he refused to accept the transfer. There was speculation he feared an assassination attempt by the rival Cali cartel, or a plot by the US Drug Enforcement Agency to kidnap him for trial in the United States.

Evidence is available that before his escape, Escobar was holding court to half the criminals of the nation. One police report showed that in the first three months of his detention he received more than 300 unauthorised visits, including many from wanted criminals, such as Dandeny Mutildenos, later captured in the US while on an Escobar mission to kill witnesses in the Noriega trial.

The former interior minister, Carlos Lemos, a critic of the surrender policy, has described the Envigado jail as ' Escobar 's operations headquarters'. Escobar had telephones, fax facilities and secure radio transmitters that allowed remote control of his crime empire.

In the past two weeks a dozen Medellin crime leaders were kidnapped and killed on Escobar 's orders. Two traffickers, Fernando Galeano and Gerardo Moncada, were blatantly taken to the prison for a final interview with Escobar .

He apparently told them they were only free because he had led the fight against extradition and made the deal to turn himself in. The others, therefore, owed him respect, loyalty and an increased share of profits. When they refused to increase the Dollars 200,000 ( pounds 111,000) a shipment tribute to Don Pablo , they were taken away and murdered, along with their brothers, bodyguards, drivers and the leaders of two other cocaine families.

Their accountant and bookkeepers were then summoned to Escobar . 'Your bosses are already dead,' he told them. 'Now you will turn over all their resources to me. If you lie you will die very painfully.' A narcotics investigator said Escobar had raised over Dollars 500 million ( pounds 278 million) in this way to finance a possible escape.

It was the evidence of these crimes that forced the government to act. Troops were told to move Escobar quietly to an army barracks, but he refused to go and demanded to see high-level government officials. When the prisons director and the vice-minister of justice arrived, they were taken hostage with guns snatched - rather too easily - from the guards.

The vice-minister, Eduardo Mendoza, later said the most savage of Escobar 's henchmen, know as 'Popeye', put a cocked Uzi to his head and screamed he was going to kill them both.

President Cesar Gaviria, cancelling his trip to the Ibero-American summit meeting in Spain, took control of the operations, ordering army special forces units to storm the jail and free the hostages. Mr Mendoza described his release as taking place 'amidst hails of gunfire and explosions'.

But by then Escobar had already left, possibly through the main gate, wearing military uniform and disguised with a gas mask to mingle with co-operative soldiers.

In his radio and televison broadcast, President Gaviria had to admit that Escobar was nowhere to be found, that the area was being searched again and again, but that the troops could not even find a tunnel complex, much less any sign of the most wanted drug baron and nine of his men. To add to government embarrassment six prison guards had been killed in the fighting. Some sources insist they were shot by the invading soldiers as they defended Escobar 's men.

The political fallout for the government is serious. Already the president's resignation has been called for, and the congress is to hold hearings to determine responsibility. But more serious is the ridicule and exasperation of the international community.

'It only corroborates what everyone told them all along about Pablo 's ability to control things,' one foreign analyst said. 'Didn't they believe their own intelligence?'

His extraordinary escape from prison shows just how far he had gained control of the political, legal and military structures of Colombia, and how his detention was never more than symbolic, a temporary arrangement that he accepted for only as long as it was convenient.

The original negotiations for a surrender agreement were the product of a long, careful campaign: over the years the men from Medellin had campaigned to convince the Colombian public that extradition was 'imperialist interference' in the country's internal affairs.

Escobar and his associates developed the fight against extradition by terrorism: the assassination of ministers, judges and police officers, and bombings that killed hundreds of civilians. The war could be ended, they made clear, whenever the government proved ready to negotiate.

The only unswerving opposition came from a small handful of indignant political leaders, and the national police, who three years ago purged officers who had been influenced by the drug mafia. They launched the Elite Force and Narcotics Brigade and dozens of cocaine laboratories were dynamited.

So Escobar began to bargain to take the pressure off and for a guarantee that he would not be sent for trial in the US. The terms of surrender were worked out through associates in public positions - the regional attorney-general, for example, who took a leading role in the negotiations, turned out to be a relative of Escobar 's.

The first decree offered reduced sentences in exchange for surrender. But it was not good enough for Escobar . He had it sent back twice for revisions that strengthened the guarantees against extradition and increased the sentence reductions to the point where he could be confident of serving less than three years.

In December 1990, the Ochoa brothers tested the waters by surrendering, and Escobar made his own arrangements for comfortable incarceration. He bought land outside his home town of Envigado and his architects designed the installations.

His lawyers haggled over details of security, establishing Escobar 's right to be protected by his own men and hand-picked prison officers inside the jail, with the army's Fourth Brigade outside, and his enemies from the police banned from a three-mil e radius.

The last step was a permanent end to extradition. Members of the constituent assembly, drawing up a new Magna Carta for Colombia, were approached by Escobar emissaries with the usual offer: 'Take our money, vote for us or die.'

Into the new constitution was written a prohibition of the extradition of native-born Colombians. Hours after the vote, Escobar turned himself in.

With Escobar inside the 'cathedral' prison at Envigado, it soon became clear that little had changed except that the army was now openly protecting the world's most notorious cocaine trafficker. Although the car bombs in public places had stopped, the country's overall murder rate continued to climb. And cocaine continued to be processed and smuggled in ever-greater quantities, with the highest purity and lowest prices on record.