Police are urging people not to hang up if they dial 999 by mistake.

Forces are asking people to stay on the line and let the operator know the call was made in error as every silent emergency call is followed up.

In Dorset, police said in recent weeks the number of accidental 999 calls had more than doubled compared with the same time last year.

The sharp rise in 999 calls is thought to be partly due to an update to Android smartphones.

A new SOS emergency function has been added through the power button and police forces have posted advice on social media for people to check the settings on their phone.

Each 999 call made in error is estimated to take about 20 minutes to resolve.

Staff check police computer systems for any previous interactions the caller may have had, and call back to check whether they need help.

Supt Pete Browning, head of contact management at Dorset Police, said: "Last month one in every five calls to our 999 service were accidental.

"Our control room staff spent over 1,000 hours in May - equivalent to 33 hours per day - purely dealing with accidental calls - time which could have been spent helping victims of crime."

Hampshire and Isle of Wight Constabulary and Thames Valley Police said its call-handlers had also seen a spike in calls in recent weeks.

Police said BT were reporting a significant increase in accidental calls to the 999/112 service following the Android update.

BT is not able to investigate all suspected misdials so they are put through to the relevant police force.