The world's largest high-performance magnet has been built by Oxford Instruments.

The company's superconductivity division, based at Tubney Wood, near Abingdon, has spent eight years working on the magnet for a US government laboratory.

It will be used in a nuclear magnetic resonance scanner, allowing researchers to map the structure of biological molecules involved in disease, and the creation of drugs.

Although part of the £5m costs have been paid by the US department of energy, the project was a huge risk for Oxford Instruments, which made provision in its annual accounts to cover the costs of successful completion.

Chief executive Andrew Mackintosh said: "Today's announcement represents a major step in reducing the ongoing technical risk in our superconductivity business.

"This is a further demonstration of how the major reorganisation of our businesses is now yielding material progress."

It will take several months to install the magnet, which builds on the leading-edge technology employed in the successful Discovery high-field magnet launched by Oxford Instruments last year, and bought by Oxford University.

Mr Mackintosh said the project reinforced the company's position as the technical leader in supplying high-field magnets, and formed the basis for future developments.