Timoleon Jimenez, better known as Timochenko, also acknowledged in an interview broadcast on Monday that the talks' opening had been postponed by several days. Under an agreement signed in late August, they were to have begun in the first half of October.
"Before speculating we prefer to think that unanticipated delays have to do with the suspension of arrest warrants," Timochenko said in the audio interview recorded at an undisclosed location and broadcast by several Colombian media outlets.
Government officials did not comment publicly on the reason for the delay but Enrique Santos, an adviser to government negotiators and brother of President Juan Manuel Santos, said the arrest warrant issue as well as the rebels' late inclusion of the Dutch woman contributed to the delay, as did bad weather that delayed travel for Ivan Marquez, a top rebel negotiator.
Santos said the talks would definitely begin by Thursday. A joint news conference is planned for Wednesday to formally mark the start of the talks.
The United States and European Union consider the Revolutionary Armed Forces of Colombia, or Farc, a terrorist organisation.
The talks mark the fourth attempt since the early 1980s to end a nearly half-century-old conflict that has claimed tens of thousands of lives.
An agenda set during six months of secret talks in Havana calls for agrarian reform, full political rights for the rebels and guerrilla disarmament once an agreement is signed.
The Farc would also get out of the cocaine trade, its chief financing source. It claims to have already halted ransom kidnappings though authorities say it continues to extort.
The Farc leader said 34-year-old Tanja Nijmeijer would be among rebel spokespeople in Oslo, where the talks are to be held at an undisclosed location before moving later in October to Cuba.
Her participation could help boost the Farc's profile in Europe, where it has more support than in the United States.
Nijmeijer gained fame when she complained of disillusionment in a diary found in 2007, four years after she joined the Farc. In 2010, however, the Dutch woman appeared in a video distributed by the Farc pledging allegiance to the Western Hemisphere's last remaining major insurgency.
Since the last round of peace negotiations were held a decade ago, a US-backed military buildup has badly battered the rebels. The Farc was granted a Switzerland-sized safe haven for the last talks. This time, it gets nothing. And there is no cease-fire.
At about 9 000 fighters, the Farc is roughly half its 2002 strength. The military has killed three of its most senior leaders since 2008.
Timochenko, aged 53, complained that the government had not provided guarantees that all delegates the Farc named to the upcoming talks would be permitted to attend. He named, in particular, Ricardo Palmera, the best-known of the rebels' five chief negotiators.
Palmera, aged 62, is serving a 60-year prison sentence in a maximum-security US prison, convicted of conspiring to kidnap three US military contractors who were captured by the Farc in 2003 when their surveillance plane crashed after mechanical failure.
He is held in solitary confinement at the so-called Supermax prison in Florence, Colorado.
His lawyer, Oscar Silva, said the US government bars him from receiving visitors and that he can only speak with Palmera, with no opportunity for confidential conversations, during hearings for a Colombian trial in which Palmera participates by videoconference.
In addition to the US sentence, Palmera has been convicted in Colombia of the kidnapping of the former mayor of the northeastern regional capital of Valledupar, where he was a well-heeled banker before joining the rebels.
Colombia's chief prosecutor, Eduardo Montealegre, says Palmera could be permitted to participate in the talks via teleconference.
He told The Associated Press on Monday, however, that the Colombian government had not yet asked the US government for that accommodation.
Timochenko called Palmera's participation "decisive" given his expertise in agrarian economics.
All but one man on the Farc's six-member ruling Secretariat is wanted by the United States on drug trafficking charges, with $5m rewards out for each.
Although Colombia's government did not comment publicly on the impending talks, one official told the AP on Monday morning that its delegation had not yet arrived in the Norwegian capital.
The official said that Wednesday's news conference would mark the talks' official start.
He spoke on condition of anonymity because he was not authorised to discuss the matter publicly.