Walter Barasa (41) "is charged with several offences against the administration of justice including corruptly influencing or attempting to corruptly influence ICC witnesses," the Hague-based ICC said in a statement on Wednesday.
Former journalist Barasa has allegedly "been and is still acting in furtherance of a criminal scheme devised by a circle of officials within the Kenyan administration," the court said, without elaborating.
The warrant, the first by the 10-year-old court for alleged witness interference, was issued on August 2 2013, but the court only decided to make it public on Wednesday.
It marks the latest chapter in increasingly troubled relations between the ICC and Kenya, where MPs have voted to leave the court's founding Rome Statute.
Barasa allegedly offered to pay three witnesses at least 1.4-million Kenyan shillings to withdraw as ICC prosecution witnesses.
He is described in court documents as a "former intermediary for the prosecution" in Kenya, meaning he liaised between witnesses and ICC prosecutors.
Opportunity for cooperation
ICC chief prosecutor Fatou Bensouda has said in the past that witness intimidation in cases against Kenya's two top politicians had reached "unprecedented levels".
"What we have discovered during the course of our investigation is that this is a network, it is not just one person," Bensouda told journalists.
"There could be other people we will issue warrants against."
Bensouda said the ICC, which has no police of its own, had attempted to have Barasa arrested "in a third country, but unfortunately this did not happen."
She said the warrant was "an opportunity for Kenya and the Kenyan government to demonstrate their cooperation they say they have been giving to the ICC."
The African Union, which has accused the ICC of singling out Africans for prosecution, will hold a special summit later this month to discuss growing opposition to the Kenyan trials.
Ruto went on trial last month, the highest-ranking official to do so, on charges of masterminding some of the 2007-08 post-election violence in Kenya that left over 1 000 people dead and several hundred thousand displaced.
Ruto (46) and Kenyan radio boss Joshua arap Sang (38) are accused of stoking the worst violence in the East African country since it gained independence in 1963.
Both Ruto and Kenyan President Uhuru Kenyatta, who also goes on trial on November 12 on similar charges, have pledged their cooperation with the court and are maintaining their innocence.
The AU has called for Ruto, Sang and Kenyatta to be tried by Kenyan courts.
Barasa had denied the charge when asked by media and said he had never met Ruto.
"I have not violated any law… Why should I be arrested?" he said.
He alleged that an ICC investigator had tried to get him to confess to working for Ruto.
"I told him to go ahead and issue the warrant," Barasa said, adding that he would address a press conference in Nairobi.
Prison or fine
Barasa previously worked for Mediamax Network, a holding company owned by the family of fellow ICC indictee President Uhuru Kenyatta.
If found guilty of using bribes or threats to influence witnesses, Barasa could face up to five years in prison and a fine.
One of the witnesses that Barasa allegedly attempted to bribe was the first prosecution witness to appear in Ruto's trial, which she did with a pixellated face and disguised voice to protect her identity.
But Kenyan media named her and published her photo, despite the ICC’s warning that legal action could be taken against anyone who identified her.
The court briefly excused Ruto from his trial last week so he could return to Nairobi to deal with the aftermath of the Westgate shopping mall siege, but he appeared back in court on Wednesday. – AFP