The investigation into charges that the government bugged telephones of judges, reporters and opposition politicians may help prospects of independent candidate Antanas Mockus.

Mockus, campaigning on an anti-corruption platform, is running second in opinion polls after a fast rise against Santos, who is closely associated with the government.

"The scandal could reinforce Mockus's support," said local pollster Jorge Londono.

President Alvaro Uribe said on Tuesday that the probe, in which five former intelligence officers were arrested, is timed to damage his government's image before May's election.

Uribe, a conservative barred by the constitution from seeking a third term, remains popular despite headlines over the last year about illegal wiretaps, questionable real estate dealings by his two sons and a long series of scandals involving security forces accused of human rights abuses.

"It is hard to think that the wiretapping scandal is going to stick to Uribe or hurt Santos's electoral prospects," said Patrick Esteruelas, analyst at the Eurasia Group consultancy.

"But it certainly can't hurt Mockus, who is capturing support from a fair number of people who voted for Uribe but who are unsatisfied with slow economic growth, high unemployment and unchecked cases of corruption," he said.

Mockus is credited with cutting crime as a two-term mayor of Bogota. He and running-mate Sergio Fajardo, former mayor of Medellin, are gaining in the polls and also enjoy wide support in the business community.

Mockus jumped to second place in the polls on Friday, the same day he announced he has early Parkinson's disease. A survey commissioned by a local television channel gave him 22 percent support, edging ahead of the Conservative Party's Noemi Sanin, who got 20 percent.

Santos was well ahead with 37 percent. Liberal Party candidate Rafael Pardo said on Tuesday that Santos should "show his face" and publicly address the wiretapping scandal.

"When this scandal occurred Mr. Santos was not the health minister, he was the defense minister," Pardo said.
 

One of five former intelligence agents arrested over the weekend said that the idea of illegally listening in on telephone conversations came from the presidential palace.

Uribe denies the charge, which is being investigated by the attorney general's office.

"What a coincidence that this is happening during an election campaign," Uribe told a local radio station.

Supreme Court Justice Cesar Valencia, whose telephone was tapped, says the bugging was ordered from high levels.

"It was a criminal enterprise directed by the presidential palace," he told El Tiempo newspaper.

The government has also been rocked by investigations showing that officials and lawmakers allied with Uribe have cooperated illegally with right-wing paramilitaries branded terrorists by Washington.

Soldiers have been prosecuted for intentionally killing civilians in order to win promotions and bonuses by passing the corpses off as guerrillas killed in action.

But the scandals have barely dented Uribe's high popularity. Many voters see him as a hero for his US-backed crackdown on drug-running rebels who have been fighting the state since the 1960s in the name of socialist revolution.

Santos is closely associated with Uribe's stance on security, which has made many parts of the country safer.

Washington sees Colombia as a market-friendly buffer against leftist governments in neighboring Venezuela and Ecuador. Investors generally expect Uribe's policies to continue whoever wins in May.

Colombian gross domestic product is expected to grow by 2.5 percent this year after expanding by a scant 0.4 percent in 2009 due in part to the world financial crisis.

(Editing by Vicki Allen)