PORT-AU-PRINCE (Reuters) - Haiti disbanded its abusive armed forces two decades ago but uniformed veterans and young recruits are resurfacing to add another destabilizing factor to the volatile Caribbean nation already dealing with a political vacuum.

Botched elections have left Haiti without a president and fractious political groups are seeking to choose an interim leader in coming days to oversee a fresh vote, against a backdrop of almost daily protests that often turn violent.

Last week, groups of men dressed in military green took to the capital Port-au-Prince in convoys, waving old weapons and sparking rage among anti-government protesters who beat to death one of the veterans.

After a series of military coups, the armed forces (FADH) were disbanded in 1995, but President Michel Martelly last year decreed they should be rebuilt, giving hope to ageing former soldiers.

A unit of military engineers was recreated, a defense minister named and some recruits sent to Ecuador for training. The pop-singer-turned-president stepped down on Feb. 7, leaving behind a rag-tag but newly motivated force that claim several thousand members.

“We demand the authorities appoint a commander-in-chief and a high command at the head of the military so we can function normally,” Jean Fednel Lafalaise, a former sergeant in his 60s who is now involved in the unofficial training of veterans and recruits, told Reuters.

Martelly’s efforts to reinstate the armed forces did not receive support from the U.S. government and U.N. officials who want to build a modern police force in Haiti and do not recognize the veterans.

“Haiti has no standing army and (we) regret recent intimidatory acts by persons wearing military style uniforms, claiming to be ex-FADH, which only served to create panic and confusion,” the U.N. special representative to Haiti, Sandra Honore, told Reuters.

Haiti has a power vacuum after a run-off election for president was canceled last month amid widespread allegations of fraud and a boycott by the opposition candidate.

With new elections provisionally set for April but still uncertain, the pressure from armed groups worries experts.

“It could be a very severe destabilizing factor to a very fragile process,” said Robert Maguire, director of the Latin American and Hemispheric Studies Program at George Washington University and a former U.S. State Department specialist on Haiti.

Even after the armed forces were disbanded, former soldiers returned as rebels to topple a government in 2004. Veterans hope for a comeback now because the army was never abolished under the constitution.

TRAINING GROUNDS

Lafalaise and his men have marched on makeshift training grounds on abandoned lots around the capital for several years, but their appearance in the capital just hours before Martelly left office last week met a furious reaction.

One of the men, Raphael Ciceron, was caught by anti-government protesters who crushed his skull with a large cinder-block.

Lafalaise said 7,000 former soldiers and 6,000 new recruits had trained since 2010 at bases throughout Haiti. The numbers could not be independently verified.

Former soldiers took to the streets on a much larger scale to join ex-police chief Guy Phillipe in the 2004 rebellion.

Lafalaise said the veterans and their recruits were no longer in league with Phillipe, who is a Senate candidate and wanted on cocaine charges in the United States. Last month, he threatened to rise up against any interim government.

“This is something different. Now we are talking about the army as a constitutionally established force,” Lafalaise said. “We are an institution.”

Prime Minister Evans Paul, who is leading the government until an interim president is selected, disagrees.

“A group of people who put on a uniform and claim they are the army without having their names registered anywhere, are not the army,” Paul told Reuters this week. “They are bandits and they will create more problems.”