By Anastasia Moloney

BOGOTA, June 21 (Thomson Reuters Foundation) - As Colombia's FARC rebels prepare to hand over the last of their weapons next week, leading rights activist have warned women are not yet playing a strong enough role in implementing a peace deal signed last year by the government and the fighters.

The deal with the Revolutionary Armed Forces of Colombia (FARC) rebels ended more than 50 years of war and was hailed by the United Nations as having an unprecedented focus on women's rights, recognising they suffered the conflict in different ways.

Talks included female peace negotiators from both sides and a gender commission to ensure women's voice were heard.

But such progress could be undermined as there is little women's participation in the peace building process, according to research this month by GPaz, a Colombian rights group.

So far 11 committees have been created to monitor and ensure that what was pledged in the accord is put into practice.

But women make up just six of the 45 people appointed - or 13.3 percent - on the peace monitoring committees.

"The accord states the need for the effective and balanced participation of women," said Beatriz Quintero, head of the National Women's Network, composed of rights groups across Colombia.

"We're saying the committees don't have to have absolute gender parity, be precisely 50-50, but 13 percent women's participation is very low," she told the Thomson Reuters Foundation.

"We're calling on both sides to ensure that during the accord's implementation the gender focus isn't lost," she said.

The government last week said more women would be appointed to peace monitoring committees by the end of June.

"We reaffirm the importance of further strengthening scenarios for the participation of women in the country and a real commitment to mainstreaming the gender approach in the implementation of the final accord," the office of the government's high peace commission said in a statement.

The U.N. Women agency says having women at the negotiating table increases the chance of a peace agreement lasting 15 years by 35 percent, while ensuring they play a key role in constructing peace also raises the chances that it will last.

Colombia's peace accord pledges to improve access to land for women farmers through a land bank and subsidies.

It also promises to investigate military forces or rebel fighters who raped women.

About 20,000 Colombians, most of them women and girls, have been victims of rape and sexual violence, a weapon used by all sides in Colombia's war, government data shows.

As part of the peace deal, the FARC is expected to hand over the last batch of its weapons to the U.N. on June 27.

(Reporting by Anastasia Moloney @anastasiabogota, Editing by Astrid Zweynert. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org)