* Truce was unilateral
* Government continued military actions
* Peace talks underway in Havana
By Nelson Acosta
HAVANA, Jan 15 (Reuters) - A unilateral ceasefire declared by Colombia's Marxist FARC rebels over the holidays ended on Wednesday, the organization said at peace talks in Havana, and it accused the Colombian government of mercilessly pursuing the war during its truce.
The FARC, or Revolutionary Armed Forces of Colombia, declared a one-month ceasefire on Dec. 15 and said in a statement issued on Wednesday, "we lived up to our word... despite permanent aggressions and provocations by the government's armed forces and police units."
Colombian President Juan Manuel Santos rejected the ceasefire from the beginning, saying the government would maintain the military pressure to keep FARC at the negotiating table, a position it has held since talks began more than a year ago.
The FARC statement said the fighting it was involved in over the last month was in self defense.
Government forces continued to attack and kill rebels in their remote strongholds in the jungles and mountains of Colombia over the holidays.
"It is a shame there is no extension of the ceasefire. It ended today," Andres Paris, one of the FARC negotiators, told Reuters on the sidelines of the talks.
The rebels are considered a terrorist organization by the Colombian government and its main ally, the United States.
The FARC has been fighting the government in a jungle and urban conflict that has killed more than 200,000 people in the five decades since it began as a peasant movement seeking land reform.
The war is the last major guerilla conflict in the region.
The talks in 2013 resulted in a general agreement on agrarian reform and rebel participation in politics once they lay down their arms, boosting Santos's standing in the polls as he seeks re-election in May.
Negotiations are currently centered on drug trafficking, with the issues of reparations for war victims and the process of disarmament still to be worked out, along with the thorny issue of what happens to FARC commanders and military personnel accused of various crimes, human rights violations and killing civilians.
The FARC, the larger of two guerrilla groups, with some 8,000 troops, has repeatedly stated that an agreement cannot include prison time for any of its leaders.
The government has been working toward negotiations with the second group, the Colombian National Liberation Army, with about 3,000 members.
The talks are being facilitated by Cuba and Norway and hosted in Havana. (Writing by Marc Frank; Editing by Dan Grebler)