POLICE have warned people to be vigilant after an increase in venomous snake sightings.

Officers in Argyll and West Dunbartonshire made the call after several instances of adders being spotted in the Tarbert area over the weekend.

Adders emerge from hibernation in March and April and can be seen basking in the sun on rocks or logs.

A bite from the snakes, which are typically found in woodland, heathland and moorland, can be “very painful” but are “rarely” fatal, police said.

A statement by Argyll and West Dunbartonshire police said: "Adders are coming out of hibernation now.

"The snake is not aggressive and usually only bites when alarmed or disturbed.

"Bites can be very painful, but they are rarely fatal.

"Sightings have already been noted in the Tarbert area."

Adders – the UK’s only venomous snake – are grey or reddish brown, with a darker and very distinct zig-zag pattern down their backs.

Black forms are also sometimes spotted.

They generally stick to the undergrowth, rarely confronting or biting humans.

Most attacks happen when they are trodden on or picked up, with their venom primarily used to immobilise and kill their prey of small mammals, nestlings and lizards.

In 2012, a hiker on Ben Lomond was rushed to hospital in Glasgow after an adder bit her as she held it up for a photograph.

Angie Roches' hand ballooned to three times its normal size after the incident while hillwalking with her fiance.

The snakes are protected in the UK under the Wildlife and Countryside Act 1981 and classified as a priority species in the UK Biodiversity Action Plan.