THERE'S no way to calculate if you are safe to drink and drive - that's the warning from police as they launch their Christmas campaign.

Police will be increasing their efforts to catch people who risk driving under the influence of drink and drugs during the party season.

Forty three people have died and 215 have been seriously injured in West Mercia over the last three years following crashes where drink or drugs were recorded as a contributory factor.

Superintendent Gareth Morgan for West Mercia Police said: "It’s extremely frustrating that some motorists still selfishly choose to drive under the influence of drink or drugs in the knowledge that their actions could kill or seriously injure themselves or others.

"Drink or drug driving is completely unacceptable at any time and catching motorists who are prepared to take such a risk is a priority for us.

"Patrols will be conducted in the run up to and over Christmas and New Year in a bid to tackle those who commit the unacceptable act of drinking or drug driving.

"The simple fact is, there is only one way of being sure that you are safe to drive and that is not to drink at all.”

Pedestrians are also being encouraged to stay safe and to plan safe routes home and to drink responsibly.

Police will be stopping drivers at all times of day throughout the run up to Christmas and the New Year.

They have warned drivers there is no foolproof way of calculating how much you can drink and remain under the limit.

Importantly, they added, it is hard to calculate how long alcohol may stay in your body if you are driving the morning after.

They have urged people to plan alternative transport such as buses, trains, taxis and sharing with a designated drivers.