Ambulance crews across the country are gearing up to deal with a 20% increase in emergency incidents during their busiest time of year.

Resources are increased at peak periods to respond to the surge in 999 calls during the festive period, with most of the incidents alcohol-related, the Scottish Ambulance Service (SAS) said.

Bosses are also said to be preparing for the challenges severe weather can bring, with around 150 vehicles fitted with automatic snow chains or winter tyres as well as others with 4x4 capabilities.

Specially equipped Land Rovers and six-wheeled Polaris vehicles also make up the fleet.

Alcohol is a key factor in assaults on ambulance staff, according to SAS. Crews have to deal with more violent and abusive behaviour at this time of year, with every instance reported to police.

Health Secretary Alex Neil said: "Ambulance crews work incredibly hard to provide the best patient care 365 days a year and at this, their most challenging time of the year, they play a particularly key role working around the clock to respond to 999 calls through all conditions and weather.

"Alcohol misuse is taking its toll on too many people across Scotland, young and old. Not only does this misuse burden our health service and police, it also costs Scots an estimated £3.6 billion each year.

"It's particularly important at this time of year, when people are going on Christmas nights out, that they drink responsibly, keep safe and ensure they do not cause any added burden for our ambulance crews."

Last year emergency ambulance crews responded to around 61,000 incidents over the festive season.

Pauline Howie, SAS chief executive, said: "Our staff work tirelessly to respond to people in need, whatever the weather conditions. They do a fantastic job and it is difficult to understand the motivations of those who abuse or try to obstruct them but alcohol and other substances are usually involved.

"Detailed operational plans are in place to cope with adverse weather and our 4x4 capacity is greater than any previous year.

"As they enjoy festive parties, we would ask people to drink sensibly and wrap up well for the weather. This will help us to focus our ambulances on responding to those people who are in most need of our help."