THE £55,000 annual fee which Scottish Enterprise chief executive Lena Wilson will earn from her one-day-a-month directorship of a FTSE-100 company is more than 50% higher than the average earned by a full-time employee at the economic development agency.

Last night unions questioned the level of pay for her additional role, comparing it to what other workers earn.

Dave Watson, of the public sector union Unison, said: "Not only is this payment of £55,000 for one day a month around one-and-a-half times the average wage at Scottish Enterprise, it is more than double the average Scottish income of about £25,000.

"When you compare it with local government workers, it is even more stark, with the average council pay being around £18,000 a year."

Critics have rounded on potential conflicts of interest over the appointment of the chief executive after it emerged this week she was adding the non-executive directorship of international quality and safety solutions company Intertek to her £200,000-a-year role as head of Scottish Enterprise.

The Intertek appointment, which has been endorsed by Scottish Enterprise chairman Crawford Gillies and Scottish Finance Secretary John Swinney, was announced on Monday.

The Herald revealed yesterday that Intertek had received nine awards of money from the taxpayer-funded Scottish Enterprise since 2010.

Amounts paid to Intertek, which has a stock market worth of about £4.3 billion, range from £600 to support a Middle East trade mission to £15,000 to help it find space for its Aberdeen operation in 2010.

Scottish Enterprise has emphasised "Lena has had no personal involvement with the company in either her present or previous roles in SE".

Asked by The Herald what the one-day-a-month role of non-executive director would involve, a spokeswoman for Intertek said that the "time commitment for non-executive directors for board duties varies depending on demands of the business and other events".

She added: "In practice, their time commitment is up to one day per month, where the core of this time commitment is oriented around their expected attendances at company board meetings, of which there are approximately eight per annum, the annual meeting and any other general meeting if required.

"Directors are required to allocate sufficient time to perform their duties."

Intertek's non-executive directors can receive significantly more than their £55,000 basic annual fee if they are appointed to one of the board committees.

The Scottish Government was sticking to its stance that Mr Swinney would continue to have no involvement in what were, essentially, decisions for the board of Scottish Enterprise.

"We have no plans to change the nature of the appoint- ment of the chief executive of Scottish Enterprise," said a spokeswoman.

However, Green Party co-convener Patrick Harvie said: "A key pledge of SNP ministers is to reduce the growing inequality in society.

"By allowing an extremely well-paid full-time public servant to moonlight shows their contempt."

Scottish Enterprise's latest available annual report, revealed the total wages and salaries bill for permanent staff at the agency was £46.9 million. The annual report shows the average number of permanent employees in 2010/11, calculated on a full-time equivalent basis, was 1299.

This gives an average, full-time-equivalent salary of about £36,100. Ms Wilson's £55,000 annual fee from Intertek is 52% greater than this.