Half of the registries in England and Wales have been told to stop using a new computer system, following "performance difficulties", the Office of National Statistics (ONS) confirmed today.

The ONS has not identified the source of the performance problem, according to spokesman, but he denied reports that the system had experienced "total system failure".

In a letter to The Times today, a registry officer claimed the software was designed for the US and its adaptation for the UK was incomplete. He was concerned that the system might be vulnerable to identity thieves and frustrated that the ONS had not prepared the system for the workload that would be placed on it.

The £6m computer system was meant to help drag the registrar's handling of births, marriages, and deaths out of the Victorian era. The Registration ON line (RON) system was adapted from an existing software system by Mantech with the help of the Office of National Statistics.

The system is to be rolled out across 420 registry offices in England and Wales in March, replacing an old system that worked alongside a manual backup registry since 1990. But the rollout was interrupted when registries started running into those "performance difficulties", the ONS spokesman told us.

"So we've taken half of them [registries] off RON and they've reverted to the old system," he said.

All registries would still use RON to record the details of civil partnerships, of which there were 14,600 in England and Wales in the 12 months to September 2005, he said.

Half were still using RON to record births and deaths. Registrars recorded a total of 645,000 births and 513,000 deaths last year.

"The plan was to start rolling out marriages in October this year," said the ONS spokesman. "We're now reviewing that in the light of the present situation."

Siemens is responsible for supplying the supporting infrastructure and implementing the system around the country. ®