* Peace talks expected to start in Oslo on Oct. 15
* Colombia, Marxist rebels to hold joint news conference
* Colombia hopes to end five decades of conflict
OSLO, Oct 4 (Reuters) - Colombia's government and FARC guerrillas will start peace talks in Oslo on Oct. 15 and hold a joint news conference on Oct. 17, Norway's government and diplomatic sources said on Thursday, as the sides strive to end five decades of conflict.
The parties are in Havana, with Norwegian and other diplomats, working to prepare for the official talks.
Colombian President Juan Manuel Santos said last week he was "cautiously optimistic" that his government could reach a peace deal with the Revolutionary Armed Forces of Colombia (FARC)rebels.
The rebel group was formed in 1964 but its membership has fallen to about 8,000 in recent years. The group is funded mainly by the cocaine trade and extortion and has resorted to recruiting children as support for its Marxist cause has waned.
FARC is considered a terrorist organization by Washington and the European Union.
"It has now been officially confirmed by the government of Colombia and FARC-EP that the press conference in Oslo is scheduled for 17 October 2012," the Norwegian government said.
Norwegian diplomatic sources said the talks were expected to begin in Oslo on Oct 15. (Reporting by Vegard Botterli and Victoria Klesty; Editing by Janet Lawrence)