Menzies Campbell said the late Charles Kennedy had faced “appalling treatment” at the hands of the SNP during a campaign visit to the Black Isle.
The former Liberal Democrat UK leader said Mr Kennedy was the victim of a “despicable campaign” when he lost the Ross, Skye and Lochaber seat to the SNP’s Ian Blackford in 2015.
The Lib Dems complained of “angry, aggressive and unpleasant behaviour” from the SNP during the last election which Mr Kennedy fought for the Lib Dems before losing his battle with alcoholism.
Speaking after a visit to the Black Isle Brewery, Lord Campbell said: “Charles Kennedy was a Highland gentleman and an excellent local MP.
“He always fought for the Highlands and led the principled opposition to the Iraq War, yet faced appalling treatment at the hands of the SNP in the most despicable campaign I can recall in all my time in politics.
“Ian Blackford has a great deal to answer for, as does the SNP High Command in Edinburgh who knew exactly what sort of campaign was being run locally.”
Lord Campbell was in the Black Isle campaigning for Lib Dem candidate Craig Harrow, who is trying to recapture the seat for the Lib Dems.
A SNP spokesman said: “Charles Kennedy represented Ross, Skye and Lochaber as a diligent local MP for many years – and in 2015 the people placed their trust in Ian Blackford and the SNP to do likewise.
“Ian has served his constituents with distinction since then, and while we take nothing for granted, we are confident that the SNP’s positive message is resonating with voters right across the Highlands and the rest of the country.”