Hostilities in Colombia have displaced or otherwise disrupted the lives of more than 250,000 children since peace talks began three years ago, the United Nations children's agency said on Sunday.

Among them, almost 300 children were killed or injured and some 1,000 recruited or otherwise exploited by non-state armed groups during the talks between the government and the left-wing FARC rebels, according to a report by UNICEF released three days before a deadline for a final deal both sides say will probably pass unmet.

"As peace negotiations to end half a century of war in Colombia continue, it is crucial to make children's interests and protection a priority," Roberto De Bernardi, UNICEF representative in Colombia, said in a statement. "No child in Colombia today knows what it is like to live in a country at peace."

The government's peace talks with the Marxist Revolutionary Armed Forces of Colombia (FARC) rebels are aimed at ending five decades of conflict, which has also involved right-wing paramilitary groups.

Although a settlement is expected soon, the talks have stumbled over the details of an eventual truce, negotiators said last week.

The peace talks have helped reduce the number of children killed, injured and displaced by roughly half, UNICEF said.

However, widespread violence has continued to disrupt lives, the agency added.

More than 230,000 children have been displaced, at least 75 killed and 180 injured by fighting, the report said.

Landmines and unexploded ordnance have killed or injured another 130 children, it added.

At least 180 children were victim to sexual violence, UNICEF said, adding that displacement, fear and presence of landmines are also causing children to drop out of school.

"Even if the peace agreement were to be signed tomorrow, children will continue to be at risk of all kinds of violations," De Bernardi said. "Unless these children receive the material and psychological assistance they need, the prospects of long-lasting peace will remain elusive."

Negotiators at the talks have announced several key advances in recent months, but a final deal remains elusive.

The goal is to turn the FARC into a political party and end a grinding, complex conflict that has killed more than 260,000 people and uprooted 6.6 million.

The FARC guerrillas have been observing a unilateral ceasefire since July. But while the government has stopped bombing their positions, it has yet to accede to the rebels' demand for a bilateral ceasefire.

On the ground in Colombia, hostilities have almost entirely halted under the FARC's unilateral ceasefire -- although a smaller rebel group, the National Liberation Army (ELN), has not joined the peace process and continues periodic attacks.