Nine primary care trusts in the south central region are to be amalgamated into three clusters, their strategic health authority has announced.

The move follows an instruction for further PCT clustering in the NHS operating framework for 2011. PCTs in London, Essex, the West Midlands and the North East have already grouped together or announced their intention to do so.

NHS South Central said the move would ensure its PCTs remained “resilient during the transition phase” to commissioning consortia.

Under the plans, NHS Southampton, Isle of Wight, Portsmouth and Hampshire – the country’s largest PCT – will form one group, Berkshire West and Berkshire East another, and the third will comprise Milton Keynes, Buckinghamshire and Oxfordshire.

However, there is also a possibility that Milton Keynes may instead cluster separately with NHS Northamptonshire, which is in the East Midlands region. The SHA said a decision – yet to be made – will be announced soon.

Each cluster will have a single executive team “in place as soon as possible”, while decisions about the remainder of their structure will follow Department of Health human resources guidance on the processes associated with cluster formation, expected this month.

The SHA said it had agreed to wait for the guidance before “pressing ahead” with the new arrangements to ensure “all affected staff are treated transparently, consistently and fairly”.

NHS Southampton, Hampshire, Berkshire East and Buckinghamshire all scored poorly in last year’s world class commissioning rankings.