* U.N. experts voice strong concerns at proposed reforms
* Fear impunity for soldiers and police accused of crimes
* Unusual public appeal comes amid peace talks with rebels
By Stephanie Nebehay
GENEVA, Oct 22 (Reuters) - Colombian military and police forces suspected of committing crimes including murder and torture in the country's long war could escape prosecution under proposed constitutional reforms, U.N. human rights experts warned on Monday.
In a rare joint letter to Colombia's government and congress, made public in Geneva, they called for urgent reconsideration of the draft reforms in the interest of fighting impunity and fostering peace.
The government of President Juan Manuel Santos and Marxist guerrilla leaders agreed last week to start peace talks next month aimed at finding a negotiated end to the five-decade-old conflict.
In their letter, the human rights experts called for a reconsideration of the proposed reforms, which would expand the power of military criminal tribunals to investigate violations committed by all sides. They said such cases should remain in the hands of civilian courts.
"Should this reform be approved, it could seriously undermine the administration of justice in cases of alleged violations of human rights and international humanitarian law, including serious crimes, by military or police forces (Fuerza Publica)," the experts said.
"We believe that such a reform would represent a historic setback to the progress achieved by the state of Colombia in the fight against impunity and respect and guarantee of human rights," they said.
Eleven independent U.N. experts who report to the U.N. Human Rights Council, including its investigators into extrajudicial executions, torture and arbitrary detention, signed the letter.
Thousands of people have been killed and millions more displaced in 50 years of war between the Colombian government and leftist guerrillas, whose grievances include the unequal distribution of land.
Negotiators from the government and Revolutionary Armed Forces of Colombia (FARC) have agreed to meet in Cuba in mid-November to start what are likely to be thorny peace talks aimed at patching together an end to the conflict, both sides said in Norway on Thursday after initial talks.
The FARC, which took up arms in 1964, funded its war by kidnapping, extortion and drugs, but has been weakened by a decade of U.S.-backed blows. Its rebels still launch attacks, increasingly against the fast-expanding mining and oil sectors.
The U.N. experts said the proposed constitutional reforms would jeopardise Colombia's efforts to prevent a repetition of the "notorious human rights violations committed in the past, particularly between 2003 and 2008 by members of the Fuerza Publica." They noted that there had been a reduction in violations since 2009.
The reform provides for establishing a Penal Guarantees Court as a control court to deal with any accusation against a member of the Fuerza Publica, the experts said.
"This provision would result in preferential treatment in their favour, including for acts that may not be directly related to the military or police functions, and make allegations harder to prove," they said.
This would imply the creation of a "parallel system of administration of justice and would violate the principle of equality in relation to access to justice for all individuals and impair due process of law," they added.
Paramilitary groups were set up in the 1980s by rich landowners looking for protection from rebels. But as they pushed back insurgents, the militias often massacred people on suspicion that they had colluded with guerrillas.
Over the last decade, scores of members of Colombia's Congress have been jailed for links to paramilitary groups, and new accusations and cases continue to arise six years after the militias officially demobilized in a government-run process. (Reporting by Stephanie Nebehay)