Uribe tweeted that he felt "morally impeded" from continuing in his role as a senator while also mounting a defense against accusations that he has he denied.

"I've proceeded according to the law and my rights," he wrote on Twitter, while decrying the Supreme Court's press release as a "pre-judgment."

For several years the powerful ex-chief of state has been involved in a protracted legal dispute related to long-simmering and vehemently denied claims of ties to right-wing paramilitary groups.

The conservative Uribe accused another senator at the opposite end of the political spectrum, Ivan Cepeda, of pressuring prison inmates to falsely state that he was linked to one such group.

The Supreme Court found no evidence to support Uribe's claim but decided there were grounds to investigate him for manipulating witnesses instead.

In a statement, the court provided few details but said the case concerns acts that took place this year. The court said that after Uribe's case against Cepeda was blocked from going forward, "People close to ex-President Uribe began new acts of manipulating witnesses."

Cepeda told The Associated Press that Uribe's associates had offered one witness a bribe in exchange for retracting accusations against the former president.

"Colombia is showing today that no one is above the law," Cepeda said.

The case comes just two weeks before President-elect Ivan Duque will be sworn into office, having handily won a runoff election against ex-guerrilla Gustavo Petro thanks in large part to Uribe's support.

Many Colombians had speculated whether Uribe would use his position in the Senate and close relationship with Duque to sway the new president on decisive matters, such as making changes to the government's peace accord with the Revolutionary Armed Forces of Colombia.

Uribe has been dogged by allegations of links to drug cartels and paramilitaries since the start of his political career in the early 1980s, when the civil aviation agency he led was accused of giving air licenses to drug traffickers. U.S. State Department cables declassified in May showed U.S. officials were told more than two decades ago that Uribe had ties to drug cartels.

His brother, Santiago Uribe, is awaiting trial on charges that he was a leader of a death squad called the "Twelve Apostles" that was run from his cattle ranch.

Uribe, in a video posted on social media, has dismissed the allegations in the State Department cables as "fake news, in electoral periods and without proof."