By Luis Jaime Acosta

BOGOTA (Reuters) -Colombia's former President Alvaro Uribe could be tried on allegations of witness tampering, after a judge on Tuesday dismissed a prosecutor request to shelve the probe, reviving a long-running and deeply polarizing case.

The attorney general's office asked in March 2021 for a hearing on potentially curtailing the investigation, after it found Uribe's conduct did not constitute a crime.

Uribe and several allies were investigated over allegations of witness tampering carried out in an attempt to discredit accusations he had ties to right-wing paramilitaries. He has always maintained his innocence.

Uribe's supporters have characterized the process as a persecution, while his detractors have celebrated it as a deserved downfall.

"Contrary to what has been affirmed by the attorney general, there are probatory elements, physical evidence and legally obtained information that affirms, with a probability of truth, that the criminal conduct of bribery did occur and that Uribe participated," Bogota judge Laura Barrera said.

She will not be the trial judge and attorney general's office can appeal the decision.

Uribe has not commented directly on the decision, but on Twitter he criticized "leaks" to journalists.

Uribe's critics have repeatedly alleged the attorney general's office would be less rigorous in its investigation than the Supreme Court, originally charged with the probe.

The influential former president, who could serve 12 years of prison if convicted, resigned his senate seat in 2020 after the Supreme Court ordered house arrest. The resignation triggered the case's transfer to the attorney general's office.

Uribe's detention lasted just over two months before a judge lifted the order.

The case stems from a 2012 allegation by Uribe, who accused leftist Senator Ivan Cepeda of orchestrating a plot to tie him to paramilitaries.

But in 2018 the Supreme Court said Cepeda had collected information from former fighters as part of his work and had not paid or pressured former paramilitaries. Instead the court said it was Uribe and his allies who pressured witnesses.

Cepeda said in a video that he respected the judge's decision and hopes it will contribute to truth and justice.

Uribe directed a military offensive against left-wing guerrilla groups during his 2002 to 2010 presidency and won more votes than any other senator in legislative elections in 2018, where his party's presidential candidate, Ivan Duque, also won.

Paramilitary groups emerged in Colombia in the 1980s, funded by landowners and others to protect themselves from rebel attacks.

The groups - accused of widespread human rights violations including murders, rapes and torture - demobilized under a peace deal during Uribe's term, though many members later formed crime gangs.

(Reporting by Luis Jaime Acosta;Writing by Julia Symmes Cobb;Editing by Stephen Coates and Sonali Paul)