The 5000-member National Liberation Army, known by its Spanish initials ELN, told the RCN radio on Friday it will free the hostages in what it called a "high risk" environment, dodging ongoing offensives by the Colombian military.
"The ELN has committed itself, and we're going to honour our word on the liberation," said top ELN commander Nicolas Rodriguez, also known by his rebel war name Gabino.
Israelis Benny Daniel, Ido Guy, Erez Altawil and Orpaz Ohayon and Briton Mark Henderson are being held hostage in Colombia's northern Sierra Nevada mountains.
Rodriguez, who has asked for a ceasefire to allow for the tourists' safe release, blasted "the government's adamant refusal to open a corridor that would allow for the liberation."
The rebels released two other hostages - a Spaniard and a German - in late November and had promised to free the remaining five before Christmas.
The eighth member of the group, a 19-year-old Briton, made a daring escape shortly after his abduction near Colombia's "Lost City," Indian ruins perched high in the Sierra Nevada.
Thousands of people are abducted in Colombia every year, most by Marxist rebels looking for ransom money to fund their four-decade-old guerrilla war.
"The ELN has committed itself, and we're going to honour our word on the liberation"
Meanwhile, gunmen killed a Colombian radio and television journalist, shooting him four times in the head as he went to work, police said on Friday.
William Soto, 45, who had reported on several cases of local corruption, was shot late on Thursday in the port city of Buenaventura, 350 km southeast of Bogota, the
capital. Colleagues said Soto had received death threats.
It was the seventh killing in 2003 of a journalist in war-torn Colombia. The Andean nation is considered one of the most dangerous countries to work as a journalist. Illegal armed groups from the right and left routinely target journalists.