KIGALI (Reuters) - Rwanda is rushing to complete a $2.5 million genocide museum in time to host next month's memorial ceremonies marking the 10th anniversary of the 1994 mass slaughter, organisers said on Monday.

Hundreds of mud-speckled men in blue boiler suits and women in colourful swathes of material are digging, hammering, sawing, laying bricks, cement and carpet and painting walls to get the memorial space ready by April 7.

Rwanda will officially unveil its shiny new genocide museum on that day as foreign dignitaries and Rwandans gather at the site to reflect on the 1994 killings, when some 800,000 civilians were butchered by Hutu extremists in 100 days.

"We're working around the clock to get everything done for the anniversary, but it'll take us every last minute," said James Smith of Aegis Trust, the British-based genocide prevention organisation behind the building of the museum.

The Gisozi memorial site, perched on the slopes of one of Kigali's many hills, is set to become Rwanda's national memorial, though there are hundreds of smaller sites and mass graves scattered like bones across the rolling green landscape.

Smith hopes the design and exhibits at the Gisozi memorial, which is being largely funded by $1.5 million from Belgium, Sweden and the U.S.-based Clinton Foundation, will be equal to Holocaust museums in Berlin, Jerusalem and Washington.

BODIES TWITCHING ON THE ROAD

The museum sits above five concrete tombs containing hundreds of coffins filled with the remains of an estimated 250,000 people killed in and around the capital.

Recently exhumed corpses will be buried in two more mass graves on April 7 and a black granite wall 2.5 metres (8 ft) high and 70 metres long will bear the names of 20,000 victims.

Visitors to the memorial will be invited to light torches with flames visible across the valley at night.

Inside the museum, visitors must descend steps into a dark, crypt-like series of rooms where Rwanda's history is carved into wooden sculptures depicting the colonial era, the build-up to the genocide, the mass killings and the aftermath.

Graphic photos and film clips will show the extreme levels of violence in 1994, with images of people being decapitated, bodies twitching on the road and wounded struggling to rise.

Some survivors involved with the memorial wanted to include simulated sounds of clubs crushing babies' skulls, but were overruled.

Instead, there is an exhibit dedicated to the countless murdered children, with photographs of everyday life - Christmas or birthday parties, holidays and school plays - accompanied by audio recordings with details of the dead.

"Irene Mutoni, aged two. Her favourite food was banana and rice, her favourite toy was a stuffed dog, her first word was daddy and she died drowning in boiling water," says one of the recordings.

"Throughout the museum, we've tried to add a personal, human touch, to give the victims a face so they're not just statistics," Smith said.

In the deepest cavern of the museum, bones and skulls will rest under smoked glass, with sepia-toned photographs of the dead in a darkly lit room, offering a compromise between survivors who want the remains on display and others who want them given a dignified burial.

"We need this," said Henriette Mutewaraba, 30, a museum guide who lost 20 family members during the genocide.