The best check on MSPs who fail to handle their constituents' cases properly is to vote them out at the next election, according to Holyrood's standards commissioner.

Dr Jim Dyer told a committee of MSPs yesterday that he thinks it is impossible to judge whether politicians are doing an adequate job according to objective standards.

He said his standards commissioner role, which was reformed only last year, should be limited to handling only matters of probity or financial wrongdoing.

He argued that if MSPs fail to be accessible or to deal with constituents' matters conscientiously, a complaint should be made to their party leaders.

The most effective way of responding to an MSP who is not doing his or her job adequately is to vote them out of office, he told the standards, procedures and public appointments committee.

"They are there to do a job which is paid for from public funds but they are not employees of the parliament," he said. "They cannot be held to a strict job description that says you must deal with constituents problems in certain ways, you must answer letters within such and such a time as an employee might be.

"They are answerable to the electorate and therefore I think the standards system should be reserved for issues of propriety and conduct, issues of transparency over financial interests and that sort of thing."

His comments followed cases in which members of the public had expected him to "pull an MSP aside in a headmasterly way and tell them to pursue an issue".

Dr Dyer told MSPs: "I think that's a matter properly for the democratic process, for the ballot box".

The Rev Graham Blount, of the Scottish churches parliamentary office, told the committee it was inappropriate to provide "black and white" rules over dealing with complaints.

Unlike Dr Dyer, he said elections were not an adequate check on MSPs and that there should be a complaints system, leaving the Presiding Officer to reach a judgment on individual cases.