Aneurin Bevan University Health Board says it will now be taking legal proceedings to take back possession of the car park at Royal Gwent Hospital in Newport.
It says it had asked a group of travellers from France, who have parked caravans in a section of the staff car park, to leave by 4pm today - but they are still on site.
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The charity says the increase is partly due to people calling for help sooner, instead of attempting to rescue themselves.
Staying windy with occasional rain, sleet and snow showers and a risk of ice patches forming
A worker at Prince Charles Hospital in Merthyr Tydfil who stole NHS property and then sold it on eBay is given suspended jail sentence.