IT problems are expected to be ongoing for several weeks following a ransomware attack which brought down the systems of 23 schools in South Gloucestershire.

The highly sophisticated attack earlier this month breached multiple layers of protection of the IT system shared by schools in the Castle School Education Trust (CSET) and partner primary schools across the area.

Joe Docherty, headteacher of The Castle School in Thornbury, said he expected a significant number of the IT systems to be restored today, but problems would be ongoing for the next few weeks.

"Staff across the school and trust have responded brilliantly to this new challenge and as a result there has been very little disruption to the classroom provision," he said in a letter to parents.

"As our Google Drive has not been affected at all, we have worked with the Trust to distribute Chromebooks and purchase the equipment to use these with our existing technology.

"The IT recovery group also managed to get WiFi back up and operational and this has meant that from Thursday, teaching staff were able to start to use this equipment and functionality to enhance their lessons as they normally would.

"We envisage IT problems will be ongoing for the next few weeks while systems are restored safely and systematically. We are expecting the restoration of a significant number of our IT systems from Monday.

"If students have stored their work on Google, as Google has not been affected, they will have not lost any work stored here.

"The IT team is working hard to restore student files stored on the network from snapshots and then transfer these to Google Drive.

"This may take some time but it should mean that any student work should not be lost. In restoring and transferring this work, we are prioritising examination groups.

"The IT team have thoroughly cleansed and checked our systems before bringing them back on line. They have also put in place additional cyber-security measures.

"These plans have been discussed with the National Cyber Security Council and police teams as well as with our IT partners and external advisors, and they are confident that the approach we are taking is safe and secure for users.

"There is no evidence whatsoever of personal data having been compromised, and this remains the case as the police forensic investigation continues."