Anti-independence campaigners have spent tens of thousands of pounds in the past week calling for tactical voting to prevent the Scottish National party winning a Holyrood majority.

At least five pro-UK groups have bought newspaper adverts, mobile ad-vans and electronic billboard sites, and numerous adverts on Facebook, urging voters to support election candidates most likely to beat an SNP candidate.

Scotland Matters, a group co-founded by Prof Hugh Pennington, a bacteriologist in Aberdeen who rose to prominence during E coli food poisoning outbreaks in the 1990s, registered with the Electoral Commission so it can spend up to £75,000 on tactical voting adverts during the election.