(Updates toll)

By Francis Kwera

KAMPALA, Jan 30 (Reuters) - A five-storey building collapsed just outside the Ugandan capital Kampala on Wednesday, killing at least 10 people and trapping more than 20 others who police said were unlikely to have survived.

The building, still under construction, was meant to be an extension to a school. It collapsed as parents and children came to a nearby administrative office but police said those trapped were all construction workers.

"The death toll now is 10. We do not expect any more people to be alive," police spokesman Gabriel Tibayungwa told Reuters.

Voices which had been calling for help from under the debris had fallen silent as earthmovers and dozens of fire-fighters tried to move the rubble, dimming rescue workers' hopes of finding more survivors.

"We heard the building shaking like there was an earthquake, we rushed down to call the foreman," said one of the survivors, Godfrey Makanga, who was working as a porter at the site.

"He said it seemed the workers on the top floor were knocking, then he climbed up to see ... Shortly after he climbed up, the building started coming down. We ran, but those inside were unable to escape," he said.

Tibayungwa had said earlier that five people had been killed and around 30 more were trapped. Since then, rescue workers had pulled out five more bodies.

The incident was the second of its kind in two years. Officials have previously warned construction companies against shoddy building, criticising some firms for using substandard materials or insufficient cement to cut back costs. (Editing by Nick Tattersall and Philippa Fletcher)

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