LONDON (Reuters) - British scientists are developing ways to use nanoparticles as tiny magnets that can heat up and kill cancer cells without harming healthy cells around them.

The researchers have found that iron-oxide nanoparticles can be attached to cancer-seeking antibodies, or injected into cancer-seeking stem cells, which take them straight to the tumors they need to kill.

Heating the cells to just 5 or 6 degrees Celsius above body temperature, in a new device called a magnetic alternating current hyperthermia (MACH) machine, can kill the cancer cells.

The researchers said the MACH device was like a microwave, heating only targeted cells.

"This offers a new way to treat cancer," the team from University College London (UCL) told a briefing on Monday.

"If we get the magnetic particles to migrate to cancer cells, we can kill only the cancer cells, leaving the healthy cells unharmed -- the ultimate targeted therapy."

The scientists said the work was at an early stage and no tests had yet been done on humans. They predicted another decade of developing, refining and testing the techniques before they could be licensed to treat cancer.

"We are aiming to be ready to go to clinical trials at the end of three years," said Quentin Pankhurst, professor of physics at UCL