The Lobbying (Scotland) Act 2016, which came into force two years ago, was introduced to increase transparency around the lobbying of MSPs and other political staff involved in policy decision-making.
However, Willie Sullivan, speaking on behalf of the Scottish Alliance for Lobbying Transparency, warned MSPs that more must be done to improve transparency around lobbying.
Speaking to the Public Audit and Post-legislative Scrutiny Committee, Mr Sullivan said Scotland was “notably out of step” with other countries and existing laws should be extended to senior civil servants.
As it stands, MSPs are required to disclose details of meetings with lobbyists to the Scottish Parliament, which is then made available to the public online.
Mr Sullivan said the definition of what is considered lobbying is so narrow “it is almost meaningless” and highlighted a lack of clarity around video calls and whether a turned-off camera means the meetings is not covered by the existing laws.
He added: “Scotland is notably out of step with other major democracies, the registers in Ireland and Canada cover all forms of communication with decision-makers however made.
"Even countries with less comprehensive lobbying legislation such as the US and the UK include oral and written communications in their definitions of lobbying.
"To meet best practice and international standards, this major loophole needs to be closed because it is avoiding transparency.”
Mr Sullivan also told MSPs that lobbying rules should extend to senior civil servants as they are not currently captured by the lobbying register.
He said: "The answers of the respondents to the committee’s call for evidence highlights that civil servants are a key target area for lobbying, ranking higher than groups like MSPs, researchers, party political staff and members of the Scottish Government.
"At the moment a key route for influencing policy is currently not being captured by the register.
"The coverage of the legislation should be extended to, at the very least, director-generals, those running directorates, and senior civil servants.
"These changes would not be a disproportionate burden when compared to other major democracies, for example Ireland, which requires coverage to extend to groups such as councillors.”