A fire involving around 4000 straw bales at a farm in Bushey today is being treated as suspicious by firefighters.

Fire engines from Watford, Rickmansworth, Hertford, St Albans and Garston were called to a fire at Tylers Farm, Little Bushey Lane, which started just after 12pm today. The farm is opposite Bushey Meads School.

The first two fire crews used breathing equipment and water jets to stop the fire from spreading from a barn to other buildings. They had the situation under control in around 40 minutes despite problems locating a water supply.

John Horastead, Station Commander at Rickmansworth Fire Station, said: "We couldn't find a hydrant out on the road for the water supplies so we were using the pond at the front of the house which was clogging up so we were running out of water."

Additional firefighters were called in to operate a fire hydrant on Little Bushey Lane.

Commander Horastead said: "We think it's a deliberate fire so we are fire investigating. We've had the fire investigation dog out going around the footpath round the rear looking for trails of petroleum spirit but that hasn't found anything. Fire investigation is carrying on. We've had a lot of help from Mark who lives here. We're just pulling the hay out of the barn and letting it burn. This is the fourth one of these we've had in a week and a half. We had one last night at Little Munden which is about a mile and a half walk up the footpath so that's suspicious. We're looking to see if we can tie the two together."

The residents of Tylers Farm refused to comment on the incident. Hertfordshire Police say they are looking into the incident and ask anyone with information to telephone 0845 330 0222.